I think there were so may more reasons. But what I see is all internal apps moving to be web based. 5 more years and Office is really going to be the last thing tying up corporates to Windows.
The only part of "Office" I really even use though is Outlook (at work), and it's pretty good at the job it does.
[0] https://support.office.com/en-us/article/how-to-install-and-...
The actual problem is the lack of Group Policy support (or even a viable equivalent - preferably one that's cross-platform).