I'm late, but I saw the thread when it was put up, I was just waiting to put my two cents in.
I'd definitely join a discord if it was moderated. I probably won't join a user-made one, though.
However, even if I were to join, I don't see myself as being very active. I'd lurk more than anything.
I generally like discord more for voice chatting.
I am in another public discord chat with about 58 members and I think I've said two things in it.
I usually read a lot, though. Also even with this many users, it's not super active.