My experience using Matrix:

*Join a few utterly quiet generic channels a-la "#type_theory"*
- One member, messages me, like "psst, come to #my_project"

*Join a somewhat active project centric room.*
- One member, messages me, like "psst, come to "#fqqu3-ktr2"

*Join a pretty active niche room.*
- One member, messages me, like "psst, come to "#_____0039"

*Join a super active ultra chaotic room with bizarre rules and members I've never come across before.*

Thinking about Maggie's blogpost.