NiHaoMike:
It takes only a few minutes or less to replace a few caps on an expensive board.
True, but a PC power supply isn't "an expensive board" these days, the cheap ones are notoriously under-engineered, and a failure has the potential to destroy some boards that are "expensive".
If a cap has blown in a switching PSU, there's a substantial risk that it's (near-)terminally stressed some other components in the process.
Even a cheapskate like me, who's been known to repartition hard drives around multi-cylinder bad spots to wring an extra year or two out of them, balks at the idea of trying to fix a PC PSU: the risk that it could literally set your PC on fire just isn't worth it.