> In the early days, if you learned the OS, those usage patterns and skilled transferred to every app on that OS

And locked your thinking into the OS' way of thinking. Every software vendor had to do their application a few times over with a different release for each OS, because the design is completely different.

As someone who uses multiple OSes (work macOS and iOS, home Windows and Ubuntu, Android) I hate nothing more than apps that behave differently on the different OSes, with different logic or features.