Some games, sure, most games, no. There are tons of games out there with dialog options that don't support choosing with numbers, a ton of games where you can't quickloot/drop with shift-click, comparing equipment is a chore, confirmation screens don't have y/enter to confirm or n/esc to cancel, missing/useless tooltips, custom fonts that are unreadable...

These things are _trivial_ to implement, it's just nobody thinks about the UI as long as it 'works'.