For some particular areas of development there is strong incentive to be on matrix. For instance most ActivityPub / Fediverse related projects favor matrix. One

For some particular areas of development there is strong incentive to be on matrix. For instance most ActivityPub / Fediverse related projects favor matrix. One example of a space that has a big collection of rooms here is "ActivityPub community" space [0], but there are plenty more. Also for the FOSS projects I'm interested in I find them mostly on matrix, and Discord, Zulip, or Slack are the exception (you could say that Discord/Slack are mostly chosen by OSS projects, and FOSS prefers Matrix, IRC, Zulip, XMPP). [0] https://matrix.to/#/#activitypub-community:codelutin.com https://matrix.to/#/#activitypub-community:codelutin.com