Discord RPing in itself is no different than its predecessors (MSN, Skype, AOL Instant Messenger). It can give you more content than a chatroom but less than a message board. There is nothing inherently bad about it and generally its a decent play-by-post system that interfaces a more casual environment. I've had dozens upon dozens of meaningful role-plays through MSN, AIM, and Skype so that argument doesn't hold a lot of water when you inspect it a little closer. That said, message board is the more detail-intuitive unless you are breaking up a post several times over.