Hidden interface controls that affect usability

Very slightly unrelated, but this trend is one of the reasons I went Android after the iPhone removed the home button. I think it became meaningfully harder to explain interactions to older users in my family and just when they got the hang of "force touch" it also went away.

First thing I do on new Pixel phones is enable 3 button navigation, but lately that's also falling out of favor in UI terms, with apps assuming bottom navigation bar and not accounting for the larger spacing of 3 button nav and putting content or text behind it.

Similarly the disappearing menu items in common software.

Take a simple example: Open a read-only file in MS Word. There is no option to save? Where's it gone? Why can I edit but not save the file?

A much better user experience would be to enable and not hide the Save option. When the user tries to save, tell them "I cannot save this file because of blah" and then tell them what they can do to fix it.