Saying "most" is untrue at most. BEsides this 25/50 Hertz shit is bollocks, we talk about frames per second, okay lame consolers?
Lots of games DID work on half the framerate to keep up with the pace but lots of games didn't.
Remember all that boasting about games scrolling in "a frame" or "50fps scrolling" ? 25fps games might have been atrue reality in the early days but later people got to learn how to properly make a game moving at a full frame.