There are mirrors for many things, like linux distributions & packages, for which universities, historically, set up mirrors, to make things faster and distributed. It also makes sense not to leave the university network in my eyes.

Apparently they don't have unlimited access in reality (see the top comment), so if someone was doing this to me - "unlimited", yeah, not really - I'd set up a mirror and slowly copy the whole thing over to avoid not being able to access the documents in case I get banned and sorting it out takes time.

I'm well aware this might be a legal problem, but blocking valid access is also a legal problem.