Counterpoint: I was a PhD student in 2004 and on the universities board* which oversaw the roll-out of the campus management system. It cost > 10m EUR to implement a shitty system with the worst UX and years of stabilizing to make it somewhat work.

The amount of corner cases and performance requirements during rush times (semester start) made it really infeasible for a university to roll their own.

* German universities have this funny system where 51% of such boards are controlled by the professors and the rest is made up of other employees/staff and students. They call it academic participation.