Backwards compatibility is not a trivial effort, and can severely constrain the future evolution of a product. Keep in mind you’re asking for a completely backwards compatible embedded device OS. Being willing to make breaking changes is part of why Apple’s software is the quality that it is.
If you want a counter example, Windows is notorious for strange undocumented behaviors and special case handling. These are consequences of Microsofts choice to fully embrace backwards compatibility. This leads to a complicated platform that is continually more and more expensive to maintain, polish, and secure.
That expensive polishing cost is what tips the scales here for Apple. Backward compatibility can get in the way to get the level of polish that they call acceptable.
> If you want a counter example, Windows is notorious for strange undocumented behaviors and special case handling. These are consequences of Microsofts choice to fully embrace backwards compatibility. This leads to a complicated platform that is continually more and more expensive to maintain, polish, and secure.
Yes, and macOS (and iOS) a POSIX operating systems that maintains backward compatibility with something from the 80s. In that regards Windows is much more modern.
It seems like a multiplicative trade-off: Apple saves a small number of hours but offloads a support burden onto thousands of developers.
I think you have to be careful about this. Apple benefits from lower costs and having more time to improve the platform; but developer time/focus/creativity is also being taxed by a constant support burden.