You are, once again, either being careless or intentionally daft. The original post you quoted clearly talked about iOS core apps when referring to the Apple ecosystem (things like iMessage, FaceTime, and iTunes in the conversation he quotes were all mentioned).
Other apps sold from the App Store aren't part of "Apple's ecosystem." They're not Apple's apps. And as you have said, paying for any app on any platform means you'd have to pay for it again if you migrate to another platform. This is true of all of them. You bringing that up to false-equate that Google's ecosystem is as trapping as Apple's ecosystem really reveals your intentions here.
The point still stands: Appel's ecosystem locks you in far more than Google's ecosystem. Google's core apps are available to iOS users. The same cannot be said of Apple's core apps. They only exist on iOS, thus leaving Apple's ecosystem is much harder.
Yes, it's also hard to lose third party apps that you've spent money on, but that's not what the people you quoted are talking about.
[doublepost=1458143265][/doublepost]
Ah, okay. Got it.