I think with the Emotion Engine (PS2) and Cell (PS3) Sony got a bit obsessed with things like vector coprocessors that are theoretically very powerful, but basically require a programmer to meditate under a waterfall for 5 years to actually master. I don't think they had a reputation for providing the best support libraries etc. either.

Of course Xbox and Gamecube also released at least a year later than the PS2, and graphics tech was moving fast at the time, so that was an advantage for them as well.