Re: The "App Gap"
I would be more of a mind that Windows Phone failed because of Microsoft's utter failure to market it effectively, their continual switching of architecture and development requirements, and, above all, the insistence on calling it "Windows Phone"...
All of the above, and the lack of apps. Of course, the architecture changes burned so many developers that the apps were increasingly less likely to come and network effects and inertia (hard to get people to buy a new platform) on top. I don't use a lot of apps but I do depend on a couple: Öffi, OsmAnd, The Economist. A lot of the rest can be wrapped in Webviews and will presumable be available as PWAs. Oh the irony!
Biting the hand that feeds IT
