Why do people keep claiming MGS4 is PS3's saviour?

[bbsin]

eliasg said:
Gears of War 2 will have a greater impact to XBOX 360 sales than MGS4 to PS3.

 impossible to find out since GeOW2 is out in the holidays where consoles always get boosted. Other than that, I disagree that GeOW would of had a bigger hardware impact than MGS4.