They were late, and while the Tile/Metro concept seemed to work OK on the phone, they also awkwardly forced it into the desktop version of Windows, where everyone I know hates it compared to the old Windows-7 style start menu. So people learned to hate Metro/Tiles, and when they saw it on phones at the Verizon store they looked at Android or iPhone instead.

It was really Google's app monopoly that killed it.

Arguing that the users did it, is the same as arguing why people only use Google or Facebook.

Google was nowhere near having a monopoly when WP died.

And yes, people use Google and Facebook because these two tools are the best in their category, not because the companies performed some kind of brainwashing on users.

Irrespective of how monopoly was acquired, it did influence choice of mobile OS. Youtube and Google Maps were of few universally used apps, not available on WP.

Neither was Microsoft a monopoly when they got their eyes sued out and a consent decree slapped on them simply for making their browser the default browser on their own OS. A lot less than Google did to stifle competition from WP.

Microsoft was definitely a monopoly when the antitrust lawsuit was filed against them. There can be no antitrust lawsuit if you're not a monopoly, it pretty much is a requirement for such a lawsuit to be brought.

It's perfectly legal (and healthy in a free trade economy) to be a monopoly.

What's illegal is leveraging that monopoly to enter other markets, which is what Microsoft attempted to do.

Did you miss the episode whereby ms belatedly tried to own web servers / web development in order to ensure a Windows client was a prerequisite to participation in the web?