Why is Nintendo expected to"Carry the Water" while Sony and MS are not?

[superchunk]

psrock said:
Let's look at this Holiday:
Gears of war 2, Fable 2, LBP, Resistance 2, Motorstorm 2, Banjo.

The truth is The HD consoles are giving us 1st party games and good ones too. It's just Nintendo sells more 1st party games.

Gears is 3rd party