The university I went to explicitly did in person written exams for pretty much all exams specifically for anti-cheating (even before the age of ChatGPT). Assignments would use computers and whatnot, but the only way to reliably prevent cheating is to force people to write the exams in carefully controlled settings.

Honestly, probably could have still used computers in controlled settings, but pencil and paper is just simpler and easier to secure.

One annoying thing is that this meant they also usually viewed assignments as untrusted and thus not worth much of the grade. You'd end up with assignments taking dozens of hours but only worth, say, 15% of your final grade. So practically all your grade is on a couple of big, stressful exams. A common breakdown I had was like 15% assignments, 15% midterm, and 70% final exam.