[@Stitches] I would very much like to make a physical copy of a book I have on my computer. Given enough time, I could complete that task by copying the words off of my computer screen and onto a roll of toilet paper. But if I have access to a printer, wouldn't it be easier just to use that?

There's certainly nothing stopping players from writing well on discord. You don't magically dumb down your writing just by moving to a chat service, no more than writing on a forum enhances ones grammar and understanding of writing. Though it should also be noted that writing these types of messages don't come flying out of the fingers faster just because it's discord. A thousand words is a thousand words.

I suppose my real concern is that I don't really see any mechanical advantage to writing on discord. In high fantasy settings where the players are expected to drop a paragraph of world building narration every time their character looks at something, my posts easily surpass the two-thousand [i]word[/i] mark. Discord's message limit is about that many [i]letters[/i], so I would need to break up those posts into many messages, which is a step I don't need to do on a forum. While I realize some people aren't a fan of it, I am also very much in love with collabs, but that's not really part of this discussion. However, the word count can get really high on those. I also like that I can turn words into clickable hyperlinks, and any pictures I do post can appear on the page at the size I want instead of as an extension. 

I really think it's mostly what you want to do. I am unwilling to put up with the handicaps discord puts on me for an RP. The only real advantage I see is that you know when someone is online and typing (unless, like me, they type in their favorite word processor) But you mentioned that you wanted to write smaller posts, and don't strike me as the sort who nerds out over formatting. I'm unsure if your players will post faster, but it certainly sounds like discord won't hold you back.