A side note, working at Unity was fun because the point was not a generic solution for all programmers, but rather to make life easier for game developers so that they could focus on the creative aspect of their games. For example Not working around Google Play Library's latest unintentional goofiness around how their Android Activitys would close prematurely and send incomplete signals terminating their purchasing flows and then you as the game developer would have to somehow magically capture the now suddenly missing workflow signal and yada yada yada. So yes, I agree with you :-)

And moving the discussion further, designing a new high level platform abstraction API could include a feature that compiles this new APIs bloat away and eliminates intermediate calls.

Platform fragmentation is kind of a never going to solve it perfectly problem in my opinion. Until we have computers that write their own software to solve some end goal, humans are going to have to keep releasing patched versions of adapter layers.