My point was more that creating a chatroom doesn’t create a community.

how would you define a "community"? And how big a deal is this effectively?
As far as I'm aware, communities (if defined as a list of rooms under a same namespace) are native to XMPP in the sense that MUCs can be namespaced at the domain level (e.g. "welcome@mycommunity.server.tld"), and then it's up to clients to do something about it. I've seen some discussions going over jdev recently but there didn't seem to be too much interest (even though clients have had a decades-long head-start to tease potential users).
IMO/IME, the "community" approach as found in discord & al. is rather detrimental and makes the relevant information hard to track because of excessive (per-server/community) rooms & notifications micromanagement. Decades old communities and projects have collaborated successfully on IRC over a single/couple of rooms and this doesn't seem like a problem in practice.
More than the proliferation of rooms, I'm more interested in threading which is seeing a comeback as of late (e.g. in Cheogram), which is somewhat more comparable to zulip and "gentler".