Players probably would not use it at all. WoW has a in game voice feature people really don't mic up using it. Even if they did use it would be a moderation nightmare in a game where they have removed chat from feast and cc I don't see SE ever doing this. I am shocked we still have chat options in FL.
As others have stated discord is not a third party greyzone. Also not presuming much when someone is arguing in bath faith, at that point the intent matters little.