I’ll throw in that RP Discord groups can be uncomfortable for people with anxiety or who lean on Internet anonymity because it adds a social pressure to the roleplaying experience that wouldn’t normally be there. It can be tough when you’re expected to assimilate in a chat room with strangers of various backgrounds, experiences, and age ranges. And there are lurkers too to consider. What happens when a person posts but doesn’t talk in the Discord? Or just doesn’t have the app...? 

Also, not every GM has what it takes to be a mod. Trust me, oh my god. 

(I’m not like anti-Discord, I just don’t see all of this stuff being mentioned.)