It's been a while (~10y) since I administered windows servers, but I recall they were much harder to automate w.r.t. maintenance. So Microsoft created M365 to fill that niche and have organizations offload operational cost to them.

With a linux fleet can run via SSH/ansible and you can patch thousands of machines programmatically in minutes and control the deploy at a fine level. With Microsoft/Windows it often involves/d logging in to the one AD server where everything runs, back it up via 3rd party software, apply the patches and hope it doesn't break, and if it does, call MS support, because rolling back is really your last resort (I feel it's become better since 10y ago, but I don't have hands-on experience anymore).

Our company runs on-prem Exchange since 2019, and... well... it's a PITA to work with (Legacy Outlook/New Outlook), we downgraded from M365 and it was really a step down in terms of features and reliability. OTOH I guess it's keeping us afloat today when M365 is having a really bad day.

Keeping your own server(s) up, including spam control, is work that takes time and costs money. Microsoft is probably still cheaper than that,[citation needed] and has more resources to keep everything running than even a medium-sized government. So it is understandable.

> Is it some sort of spying thing? Incompetence

It’s Microsoft we’re talking about so I feel like the latter is a given, and the former is a reasonable assumption.

Jokes aside, it does seem that somehow these hyperscaler cloud providers who tout the reliability of their multiple zones and global distribution sure do seem to always have some central dependency or single point of failure. AWS for example seems to have a global outage once every year or two at this point, or like us-east-1 problems always seem to affect other zones too. You’d think with their scale these clouds would be completely decentralized and redundant but apparently not.