Well I never said which one had to be "main," but when each particular console and the PC all have titles exclusive only to them, I think it's rather silly that a concept of "main" has to exist in the first place.  I play the hell out of FS, Half-Life 2, Team Fortress 2, Descent 3, and any number of other titles on my PC.  I go crazy on the Mario and Zelda series on my DS, N64, and Wii.  I hit up the PS2 for the original Guitar Hero games and old-school fun like Twisted Metal 2.  I think it makes much more sense to operate like that, to go by the games themselves and use the respective systems accordingly, than to absolutely limit yourself to a single platform and ignore anything not released on it.