It's kinda hilarious/sad that MS Office essentially developed their own UI framework which, as I understand it, was unavailable even for other teams in Microsoft, so stuff like ribbons and "advanced" pop up menus got reinvented even inside Microsoft, not to mention countless times outside Microsoft.

So much of this is self-inflicted on the part of Microsoft.

Not unique to Microsoft here, there was an android police article where they identified like 10 inconsistent action bar implementations from Google apps then a follow up a year later doing the same for navigation drawers when they were the android UX elements Google were pushing most