I don't believe that accessible community-building platforms are a problem. Nor do I believe it's something that can be solved; people will understandably congregate on platforms that are easy to use and that their friends are on.

Is the only healthy Internet one where there's 500 different platforms and to try and build a community you have to be an IT worker? How is it a bad thing that someone can hop on Discord or - indeed, as much as you might hate to admit it - Facebook and effortlessly create a group for their friends or local club?

Centralization is not the problem - it's what those companies can do with their power and data that is the underlying problem. And attempting to de-centralize things won't solve that problem - either some platforms will grow to a point where abuse happens, and/or the point of abuse will lower over time to cover those smaller platforms.

Without, for example, data privacy laws, nothing will change, whether we're on 5 platforms or 500.

(As a brief aside, since you brought up IRC in TFA... is it at all relevant that, even then, there were like 5 main networks?)

Reddit definitely feels homogenous to me. Yes I know, smaller subreddits etc etc, but it’s built on the same engagement infrastructure that is the basis for so much of the modern internet.