Play Bayonetta on PS3 and you'll find that argument is invalid. It still comes down to developer competence on their chosen platform. With PC, it takes user competence to not complete screw their machine over and then expect it to run. A good PC developer knows how to troubleshoot issues on the PC, it's part of the territory. How much PS3 or Xbox troubleshooting do you normally have to do with a game? Not a whole lot, but the games are still bug filled, can crash, and can have performance hits. My friend's 360 crashes more than my Windows 7 computer ever has.
It's called freedom. Which has responsibility (See, Risk Management). Such as consumer responsibility to understand if it'll work on their chosen hardware/software combination or not. With standards comes rigidity, and eventually comes a monopoly. Ain't it a *****.