This is a classic example of two divisions who cant get along, both fighting for the same territory.
It becomes painful when you type in your username, to have to wait for it to ask work or personal TWICE, for EVERY SINGLE MICROSOFT APP. Word, onedrive, skype, sharepoint sometimes prompts 3,4,5 times in a row with slightly different interfaces. I shouldnt have to type my O365 password EVERY SINGLE time I open a Microsoft app on iOS (except outlook which only forgets it like once a month)
A new user would get prompted for their password
1) sign into windows
2) activate office
3) sync sharepoint library
4) sync sharepoint library didnt pass the last cred to the app right.
Microsoft's credential management is atrocious for end users. Guess how many times Chrome and Facebook have made me retype my password when logged into my own computer this year.