The design and intent are bad, but let’s not discount the large amount of bad engineering too.

WinUI 3 was upgraded to stable/release when it had literally thousands of outstanding issues, including stuff like [fully replicable] 'using drag and drop causes the program to crash.' That was about the time I started opting out of the entire MS ecosystem after investing decades in it.

I can't even imagine the chaos they must have going on inside for them to be failing the way they are on the outside. I'm also curious what started it. They've never been a pinnacle of engineering, but things went really went downhill hard in more modern times.