I think that Discord as a platform has a great feel to it for flash-style RPs, but I dislike the stream-of-text behavior of the application itself. I and my group switched to a forum (from ifunny, no less) almost a decade ago because we wanted to be able to reference history and events from years past, which requires some sort of page system. When posts are on Discord, they feel pretty ethereal since they're mostly gone when they leave the top of the screen. You can find them, sure, but it's usually more painful than it's worth.