superchunk on 12 March 2013
It doesn't have to be equal in power. Just similar enough in architecture and power to have the scale-able engines allow it to run.
Same reason PC games have a wide variation on specs needed to run the game.
WiiU is closer to its PS4NXBox than Wii was to PS360 in terms of raw power and nearly identical in terms of architecture/technologies that can be used.
Essay Pro