Money, according to the LVRJ article, they dropped comps for everybody EXCEPT their top teir folks. So if the original poster was not top teir, hence they got their comps dropped. From what I understand, once the reservation is made, all of the play requirements are done at that time not when you get there.
Else if you don't come to Vegas one month, I can cut off all of your comps and say you are not playing enough to earn the comps. Not a good business model to be using.
Casinos don't keep track of where your booking your trip. They only keep track of rooms at their place and no where else. The casinos figure if they can get you to stay there, they have a good shot to keep you in their property and spend more money. Why give away free rooms? To keep your a$$ in the casino and spend money.