That's a bizarre conclusion to come to. The real motivation is that if you know apps are reflecting into your internal implementation details, and you want to m

That's a bizarre conclusion to come to. The real motivation is that if you know apps are reflecting into your internal implementation details, and you want to make a change, you're stuck with a bunch of bad choices. 1. Break the apps. Users tend to get annoyed when they upgrade the OS and their apps stop working. 2. Maintain a compatibility shim. Depending on what the change you're making does, this might not even be possible. Assuming that it is possible, how do you know what needs a shim and what behavior is actually expected? 3. Give up and do something else instead. Things get worse if you consider that OEMs may want to modify implementations as well, so you'll end up with apps that work, except on some devices. There's no sensible way to prevent app breakage when there are apps depending on your internal (and explicitly private) API; the solution is enforcement.