You can also use one of the many open servers or the main Matrix one. It doesn’t matter, it’s all encrypted and federated.

It kind of does matter though...Maybe not a ton to those just chatting in them, but if you're relying on someone else's hosting, it's only as good as long as it's hosted (and as good as its admins/mods). Part of the reason I'd be a little more interested in sorting out hosting for smaller scale chat stuff myself, as of the many things you could self-host, it's up there as one that makes more sense to me.

Also just checked out Delta.chat, and that's pretty sick! Thanks!