I've been having to use Windows a lot more lately (after barely touching it for 15 years) and the word "nightmare" is an apt description.
I think, though, I've come to realize why: backwards compatibility. I've seen videos where people have installed Windows 3.1 and then upgraded the OS from there and pretty much everything continues to work. I think in one video I saw, Quake or Doom stopped working after one upgrade (probably Vista) and then started working again after a patch release or something.
I have to hand it to Microsoft that they honor backwards compatibility as well as they do. However, at some point, you have to just make a clean break. You have to acknowledge that what you have is bad and broken and should no longer exist in this world. Microsoft finally did just that with Internet Explorer and then (to a lesser degree) with replacing Edge's rendering engine.
For Apple, backwards compatibility isn't a sacred cow. They're more than willing to throw something out that is old and/or doesn't work as well as it should. They handle breaking that fairly well, all things considered. They give plenty of notice (sometimes not as much as they probably should have -- https://arstechnica.com/gadgets/2018/01/apple-prepares-macos...) so average and power users alike have the time to transition. Sure, it's never as smooth as we would like but what transition ever is? Still, Apple users don't have to deal with things like Windows users do.
Microsoft needs to start making a clean cut with Windows, probably starting with the Explorer shell. It's old. It's obnoxious. It actively gets in the way and makes me less productive. They can do this if they just put their shoulders into it a little. (Christ almighty why does the scroll bar have to jump back to where it was if my mouse veers away from while scrolling? "Because that's how we've always done it!" is easily the worst answer to any question ever asked)
Also, for the love of all that is holy they need to reverse the decision to have ads built into the OS. How can they not see how bad an ad-centric model is becoming for Google and Facebook? Having a whole OS where the user is the product? That's a privacy nightmare that makes Google and Facebook look like little league.