alt Hacker NewsThat's not what they mean. As a developer, the API you used to develop your app was now deprecated with no migration path. That meant your app was deprecated, with no migration path.
For an app platform already a distant third place and struggling to attract developers, pissing off the few devs you do have TWICE was not a smart move.
Even then, that happened at most twice as you say, not three times as the other poster said.
And I disagree with your implicit claim that the WP7 & WP8 Silverlight -> Win10 UWP transition had no migration path. There was >= 90% source code similarity, bolstered if you had already adopted the Win8.1/WP8.1 "universal" project templates. And Microsoft provided tooling to ease the transition. Sometimes it was literally just s/Microsoft.Phone/Windows.UI/g.
Games were a different matter, I'll admit. XNA as an app platform had no direct replacement that was binary compatible with Win10 desktop, but even then, not only was DirectX already available from WP8.0, but Microsoft invested in MonoGame as an XNA replacement precisely because they knew the end of XNA would hit hard. (In fact it was the Windows Phone division that had essentially kept XNA on life support in its final years so that WP7 games would not break.)