Breja: Sure, controllers for PC exist (I have no idea why, but they do). But they ae not, thankfully, the primary way of playing games on the PC. At least for me there is no controller = PC gaming association, but maybe because I find a terrible alternative to M+K. Hell, many PC games are straight up unplayable without M+K. You ain't gonna play Heroes of MIght & Magic or Secret of Monkey Island with a pad.
Yeah, to each their own I guess. I had a time where I had problems with my left hand because of a pinched nerve, that was only diagnosed years later, and could not use WASD navigation in most cases reliably. Control by controller was a godsend back then, and I still prefer the controller where available.