I agree with most of what you said, apart from Slack in practice.

> on Slack I'm immediately get shoved into a car and driven away to discuss (I don't feel community)

It completely depends on the community / people. I'm in multiple slack servers where the threads are an exception for things that would otherwise really pollute the discussion. But otherwise, everyone just chats mostly in #general (or different rooms if the community is really large)

Slack depends heavily on the vulture that you build around it. I've been in companies where it was either everything in the specific channel (Discord like)/dm only, and in others, where threads have worked wonders. What caused this?

Different people at the wheel making decisions on how we will all use it, and encouraging the structure.

agreed, slack channels can definitely have the "lived-in space" feel to them (which is feel is the key point to the GP's comment)