Not so sure. I was in a research lab at a similar school a couple decades ago. There were two staff lab assistants (not sure they'd be considered administrators by any stretch), and the PI shared an executive assistant with three other PIs. That's not a ton of local overhead.

At the department level, there were of course deans, provosts, counselors, admissions people, etc etc etc, but even that departmental overhead wasn't more than maybe a 1:8 ratio compared to the number of grad students.

I'm sure there was similar or even greater proportional administrative staff once you got to the university level, but even if you include every single employee in big departments like Research and Graduate Admissions, it wasn't anywhere close to even half the number of students. I know this because the entirety of the administration fit into a few old buildings in half the campus, while the rest of the buildings on that half and all of the buildings in the newer part of campus were filled with labs and classrooms.

So in the ensuing twenty years, administrators have either gotten massively worse at their jobs and required far more of them to accomplish the same things (running directly counter to the general trends in worker productivity in that time), or they've created an immense amount of new make-work for themselves and their colleagues. Articles like this point pretty strongly at the latter explanation.