"No, I will host or join OSS communities on closed proprietary platforms. Never again. No, I will not join your Discord. No, I will not participate in your subreddit. No, I will not follow your project updates on Twitter."
Matrix, Discourse, and Mastodon exist are are used very successfully by a number of high profile projects. They don't force me to use proprietary, inaccessible, insecure, Electron-ridden clients. They don't force me into draconian privacy policies. They don't force me to prop up VC-funded money pits that will eventually come back around to extract anything they can. They don't treat the closed edges of their platforms as moats by which they can, ooh yeah, build a user base and then eventually hinder the experience in order to extract their deserved profits.
These things matter but people are so short-sighted and forgetful that they just jump from proprietary platform (cough, password managers are another great example), and then inevitably have to jump ship again in N years. Maybe I'm the odd one, but I'd much rather invest a bit more upfront, and deal with UX growing pains, than keeping throwing my knowledge, time, overall investment into a pit that ends up burned by capitalism.