That's because "normal" users don't know any better. They don't know what their hardware is capable of, so they don't know that their software is slow, so they don't complain about it. If they do they usually blame hardware.
I've recently been amazed when cracking an old cryptanalysis puzzle at what Python can do in very little time. But I have no idea what a responsive OS feels like on a general standpoint. Should I try to compile Firefox on Windows 3.1? (Just kidding on this last one, obviously.)