Calling it inferior or underpowered is a pretty lame way of telling that story guys.
For running a PC title like Doom, it absolutely was. The system was built around an 8-bit CPU and tilemaps and sprites, and the Mode7 stuff was hardwired only to the background layer. The machine was totally inferior for running anything that required rendered graphics. Everybody wanted to play Doom back then, but releasing it on every platform under the sun was just a bad idea and disappointed many, many gamers.
SNES has the specs of a 1990 PC because that's when it was designed and released.
Hardly. Both the NES and SNES were designed to be dirt cheap to manufacture, and were based on early 80's designs. Nintendo was always famous for their philosophy of "withered technology". The N64 was an anomaly and one of the few times they tried to push technical boundaries.