Wasn't stack ranking in use during Gates's tenure as well?
Ultimately the answer doesn't matter to me. The company has always been a bully, both in the marketplace and internally towards their staff. No one wants to see a bully succeed.
Edit: Wikipedia says "Since the 2000s, Microsoft used a stack ranking similar to the vitality curve." (http://en.wikipedia.org/wiki/Vitality_curve#Criticisms_of_ra...) Ballmer became CEO of Microsoft January 2000.
[1] http://www.alexstjohn.com/WP/2013/08/30/microsoft-review-tim...
Besides, I gave up rooting against Microsoft years ago. I just don't care about any of their products anymore.