Different main RP formats.

RPG is slower paced, has more easily organizable tabs to do things in, offers a decent interface for formatting, and optimal for long posts.

Discord, for 'snapshot' line by line roleplaying, is by far superior. Real-time, simple enough to use, even lets ya create actual accounts to represent characters in a server you can create and organized as you see fit.

They have different purposes, the way I look at it. Ultimately, RPG's format agrees with me far better. They have strengths and weaknesses; I don't believe one kills the other.