many universities bought into the cloud offering back when it was still live@edu, shown as an upgrade path for existing on-premise dovecot/exchange systems. back then a student would be lucky to get more than 100mb for their mailbox, and maybe a gig of personal file storage (which was only accessible on campus or via a vpn, the latter many would not have access to). microsoft just offered a _better deal_ at the time

frog boiling means that many never noticed how big (and therefore unspecialised) microsoft was until it was too deeply integrated

It's much better UX if everyone within the company uses the same office suite/email, it makes collaboration much nicer when everything is well integrated. And people get used to one system.

My guess is that having duplicate system would cost (in money for double subscriptions and lost productivity) much more than the benefit of being available 0.01% more. Especially for universities where almost nothing is really urgent and can't be delayed by a day.