That makes sense I guess.
IRC channels are spread over thousands of servers though and not really discoverable or, in general, mainstream user friendly
And obviously it doesn't have to be a # character.
And obviously it doesn't have to be a # character.
All that aside, parent is right, you're basically re-inventing IRC. A more user-friendly client may be a good idea, but it's something that's really hard to make money on, so it's unlikely anyone would bother working on it.
Anyway, as someone else let me now, kik intruduced exactly this feature with the exact same limit on users in one chat already.