Windows Phone aesthetics was repulsive to most people at that time; we finally got TrueColor 4k screens and all MS could do was to use 10 colors everywhere and start the flat fad that destroyed UX on most systems. What a waste.

I don't think that's quite accurate, the screens of the time were more like 480px wide and I don't think most people had a strong aesthetic opinion. Just look at Android. The major problem is that whatever app you cared about, whether it was your bank, Facebook, sport news, or Uber, or Google Maps, or whatever, it was on iOS and maybe Android. So at least in rich countries the decision tree was: buy iOS if you can afford it, buy Android if you can't. Apple basically got extremely lucky that the native app thing took off instead of their original vision of everything via the browser.