Kinda hard to have anything private here without end to end encryption. You COULD use GPG in PMs, but then people have been encrypting their email for decades too.

And with email you don't generally have to keep up with instance politics to know where to sign up to be able to email the people you want to email. So I'd still say email is simpler to use. Maybe not simpler underneath on a technical level, but that doesn't matter to the end user.