Although "biggest insult" is over the top, its part of a pattern of Microsoft providing annoying "help" that makes their software distracting and harder to use, and in aggregate really does insult the user.

Opening documents in some weird "reading mode", popping up that I can pick up where I left off every time I open a PowerPoint, adding captions to my photos I add to documents (and sending my confidential data to their servers so their ML can tell me that a chart I added is a picture of a chart), "looks like you're trying to write a resume", I'll denote my three points (a), (b), and ©, how would you rate our product, etc etc.

Some people may want this stuff, I want my computer to leave me alone and let me work. MS has a pattern of disrespect to the user that overall I agree is insulting.