[wilg]

Well, web apps could kill their desktop platform because you can have the same experience cross-platform, so why buy a Mac? It's in their interests to ensure that the Mac app is substantially better than the web app by integrating more deeply into the OS. So offering a single framework that can do a great job on web apps and an excellent job on Apple platforms, you ensure that it's the most attractive option to developers who would otherwise build an Electron app. And you ensure that most cross-platform apps (which is most apps) are better on Apple platforms.

(If they get there first, this has a side benefit of preventing Windows, Linux and Chrome OS from doing the same thing as easily.)