I’ve lived through the near demise of Apple in the late 90s before they rehired Steve Jobs, all the way through this recent renaissance of the company with it being valued at over 300 Billion USD. There are a lot of factors to their success in recent times, and one of the consistent aspects of the company over this time has been the idea of “isolation” not just in the software, but in the hardware as well. To me, Apple computers, devices, and software are the most incompatible computer systems in the market, and engineered purposely to that end. I mean incompatible as in incompatible with pretty much anything except another Apple product (if and only if they allow your device to be compatible with it! )They have almost always been like this with the exception of the brief appearance of licensed power-pc Macintosh clones in the early 1990s, but that new product strategy proved near fatal to the company.
By incompatibility, I mean not adopting standards, and/or creating in-house solutions for many hardware and software products, and furthermore deprecating industry standards prematurely or before others do. There are many examples like them using things like lightning cables for connectivity, dispensing with floppy drive, the CD drive, USB-A , etc. On the software side, deprecating things like 32-bit binary compatibility in MacOS, using proprietary file systems, proprietary BIOS/Firmware architecture, proprietary graphics stack (metal) and depreciating the most widely supported graphics API, openGL, etc Furthermore, the Proprietary browsers Safari in iOS and iPadOS and banning alternate browsers as well, are all a part of the larger strategy. There are a plethora of examples of all of this, but the main point is that this is how they do business. From using iMessage and refusing to even license it out to other manufacturers, to only allowing applications downloaded from the AppStore on iOS and iPad OS, these incompatibilities and restrictions are a core part of their business. The brilliant advertisement they are known for really sums it up: “think differently”. They purposely will do things different to not only make the user feel that they are in a special alternate universe when using their products, but also as a psychological que to condition the user to expect that things will not work as in any other hardware/software combination.
Having their hardware and software be purposely incompatible with existing and rival systems is a high level strategy that allows them to have enhanced user retention, as well as an extreme amount of control over their users behavior. By enhanced user retention, I mean the mac users that I have met throughout the years who as computer users have much less troubleshooting abilities or critical problem solving abilities in terms of general computer usage as a result of just using Apple products their whole lives. These people have grown up with working in MacOS or just even an iPhone, and so having “options” and “choices” are a foreign concept to them, and when faced with the prospect of using an alternate OS like Windows, or god-forbid Linux, they are physically revolted and frozen in fear and lack of understanding. I don’t mean to denigrate or stereotype Apple users, as I am one (although not until late in life lol!), but I’ve experienced this first hand and it is fascinating. Apple will totally retain those users, and indeed they have worked hard at it. Apple is excellent at using their incompatible software and hardware to lock the user into their ecosystem, as well as limiting the user choices which is ironically interpreted as “easy to use” by the public. We can certainly debate whether incompatibility and lack of choice makes a computer easier to use, but in any case the public accepts this trade off at least for the feeling of things being easier to use. (Try external monitor support on an M1,M2 and tell me it is easy to use LOL!! 
whoops… better buy a $1600 fully compatible Studio Display to get my 5k no-subpixel-antialiasing crisp monitor LOL)
All of that said, it is obvious they are doing something right at least if raising the company valuation to 300 billion is any indication. What it comes down to, is that the super high level restrictions in compatibility and overall user choice does give Apple one huge advantage- their computers work more like appliances than general purpose computers as most people would use them. A large segment of the population loves this and does not really want to have to think about how to troubleshoot software or tinker with settings and so forth. Indeed, I’m a battle hardened veteran of using PCs, all the way back even earlier than Windows 3.11/Ms Dos 6.22, and have spent a lifetime more or less in front of a computer. In middle age, I am finding myself appreciating the fact that my M1 Max macbook is as almost consistent as some sort of home appliance. The OS never has to be restarted, which was a concept that was not a part of my life as a Windows user, or even a linux user previously. It wakes up from sleep consistently and overall I have to say that for the limited things it can do, it does them consistently. The touchPad is the most outstanding touchPad I’ve ever tried and the hardware is super high quality. Could those features be available with less restrictive and incompatible software and hardware? Likely yes, but for whatever reason, the competition can’t nail it down, and since they can’t, Apple wins my business for portable computing. I also have an M2 iPad, which is an ultra-appliance, and if I had an option for a tablet that was as well built, powerful, and as great a looking display as it has, I’d likely choose it but there really isn’t one that has the hardware plus the apps available to compete. The galaxy tab s8 ultra was tempting but the android app ecosystem is a little anemic at the moment.
So now back to our discussion- about Safari and WebKit. The App store is big, and I mean big, business. It is not just the 30% fee that they are getting per app, and the $100/per year developer subscription cost, but it is also the fact that they become the gatekeepers as to what software they allow on their platforms. This gives them the ability to not only look/lift of the source code of any software that touches their platform, but also especially in the case of iOS, collect much, much more data from users and their apps than would be possible if the App was a webApp. Apple’s main argument for limiting iOS and iPadOS to Safari is for security, but in my opinion this is nothing more than a mob-style protection racket sold to the users and explained to the regulators in creative ways, but if it walks like a duck, and talks like a duck, it likely is a duck LOL.That is what they are doing. The reality, is that because of the restrictions built into the web platform as a whole, it is arguably MORE secure than a native App, because the data is then brokered only between you and the webserver (or whoever your browser leaks data to), rather than being exposed deeply into the OS, and in this case, Apple.
So it is absolutely in Apple’s best interest to not allow other browsers on their platform, and for the browsers they do have, make sure they are limited in functionality enough to discourage the use of webapps. Furthermore, if I were Apple, and a huge new technology like WebGPU were on the horizon, I’d plan on making sure we are amongst the founding members of the W3C WebGPU group for Safari, and then we can delay the rollout of the spec by allocating as limited funds as possible to our engineering group, while also dropping several poison pills along the way(SPIRV) to slow the development further. Ultimately this gives us the ability to gaslight anyone who criticizes our slow rollout to Safari by saying “but we were founding members of the team… we wanted this the whole time”… /s. 
That is a hypothetical scenario, but given what we know about Apple’s treatment of Flash and WebGL in Safari, I wouldn’t put it past them to get ahead of their biggest competitor to the App Store: the Web.
The force of Law and regulations are the only way they will open up for alternate browsers in iOS and iPadOS. Despite some rumours in the last year that alternate browsers are coming, I have my doubts, at least as far as iphones in the united states are concerned. Our weak regulatory framework as it pertains to technology basically means we have rely on the EU to make the push. Fingers crossed that they do. Because until then, Safari will be the platform that your WebGL 2.0/ WebGPU apps likely not work or be so buggy that it is not really worth the effort. Defective by design if I ever saw it!
Sorry for the rant. 
I’m passionate about Apple and their business practices!
I could not understand how apparently newer monitor than these 14" balloons was not able to do such a basic thing as color. to this day this remains a mystery to me. maybe they paid more money for the patents covering ray control for non-round surface, so they had to pay less for actual screen, Idk. but the fact I learned was, black and white screens could actually be better than color ones.
you expect the strongest player to weaken themselves for no reason other than that other players would welcome this development - and this is not much of an incentive, is it.