My company recently switched from a "roll-our-own" mix of old-style open-source applications to Office 365 for mail, calendar, messaging, chat, online-storage, etc. It's been a royal PITA both for the users and for us in IT/Support. Things are broken every day, and the list is growing, not shrinking.
Just now, Microsoft is not one of my "They Get It Right" vendors.
“My company recently switched from a “roll-our-own” mix of old-style open-source applications to Office 365 for mail...”
MS Office 365’s Outlook web front end is just awful. They took the (just OK) Outlook local front end and absolutely ruined it.
Coders are addicted to constantly changing things. They CANNOT leave well enough alone (it’s effectively a Coders’ Jobs Program).
Imagine if car dealership mechanics had their tool chests messed with by others very few months, overnight — tools changed, items rearranged, locks changed. They would be totally pissed off.