Depends on the university but for mine in particular discord is the primary communication method for clubs, and also friends to a certain extent. I think discord is decent for privacy but I don’t fully know, what I do is have my publicly visible profile be pretty anonymous and not tied to me.really at all, but then you can make server-specific profile names with your real name.
I’ll admit I’m not the most privacy-oriented person, I try for a somewhat decent level of privacy (using Firefox+unlock, bitwarden, signal for family chat, a few other things) but also do have Snapchat for instance, which is one of the worse things I do. This does remind me tho that I should try and convince my roommates to use signal instead of SMS because they have iPhones and I’m android so it’s kinda awful for anything but text
I think because simpleX is more open source, self-hosted, and maybe slightly more anonymous. Not sure how the usability trades off for that if at all because I haven’t used it (I mainly use signal and discord)
It also doesn’t seem to be a mass migration by any means, just that simpleX is a bit better if you are super hardcore about your privacy.