GUIs used to have this too of course. Alt-F to bring up the file menu, the hotkey was underlined.

That seems to have slowly vanished over the last 30 years

I still have this and I loath programs that breaks this consistency by shipping their own graphics toolkit stacks. This is a reason for me to deinstall a program and never use it again. Programs that are not 3D games or specialized CAD programs should only be allowed to use the OS graphics stack and nothing else. (This includes programs shipped by the OS vendor.)