While true, there are neverthless regulations (in the US at least) that prevent (in principle) universities from forcing students to use third party tools that the school has not explicitly vetted to comply with FERPA (The Family Educational Rights and Privacy Act).
Of course, people ignore these regulations all the time, and most of the time no one makes a stink, but if you try to be a stickler (as I do) then it can be a real pain. I had to use our institutional OneDrive account for one department and gdrive for another because the different departments had different institutional accounts for their students. Of course all students already had Dropbox and Google drive accpunts, and the ones that had to use one drive especially begged to just use gdrive, but the lawyers were insistent.
Stupid? Yes. Alas, necessary if you want to comply with the rules.