We're talking about running a few mail server, network shares, and an office suite (LibreOffice if you want). Any university's in-house IT department should be able to pull that off, and it's exactly what many did for a very long time.
The trap of Microsoft is long contracts and setting up dependency. In many cases it was a big undertaking to get the current setup, now try convincing anyone to tear it out.
If Universities are anything like other large public/public-adjacent organizations, the bulk of the in-house IT department was long since replaced by Microsoft resellers posing as IT. It’s insidious.