You probably know this site already http://www.html5gamedevs.com
A platform like this would be already lightyears better than discourse in my opinion, even though it’s just wordpress with a community plugin. They actually only pay attention for Babylon, THREE is only mentioned in a subcategory about 3D.
Even if they would have an actual THREE category, the platform isn’t THREE dedicated and targets designers and game developers only, those who want to shoot out games as much as possible to monetize them, so they only list libraries which come with a full integrated engine package.
THREE definetly needs a platform where people can also upload packages in a categorized “store” thingy you can also add pictures, with a fancy modern design. That makes publishing code/resources more worthy (instead posts here which will drop into the dark). And it gives people a much better impression of THREE, as looking at Github or here everything is just like a blank continuos issue stream. Besides the packages themselves receiving better support, it also pushes the popularity of THREE.
Beginners will always look at what it offers, no one would just browse through this tag based forum, the first thing people probably will look at are the examples at threejs.org, but these are manually picked and aren’t complete out-of-box systems which are randomly distributed at Github and other sites. (like a library for a platformer, for a complete particle system with editor etc.) They want to see if it offers a complete stack to develop a app or game with a big community with lots of ready-to-iuse things.
I mean everyone could setup this kind of platform, but if it doesn’t go a official route, it’s likely that it will just stay in the dark.
Edit: i noticed this went slightly off topic