It's the generalizations like, "...tipping everyone in the hotel...." that make the top on the worm can loosen. I've found that the only folks other than waitpeople I tip at Disney are valets, bellpersons and housekeepers.
That article was in USA Today and their rationale was that each valet would have about the same number of cars every shift, so if you tip only the person who returns it, then everything should even out among the bell people. I disagree with this, however, because I tip based on what services are performed for ME...I try to leave all the outside factors out of it...Like how many cars they have, what their rate of pay is, whether or not I feel that valet is a downtrodden job category that should not be 'begrudged' a tip.
If they take MY car to park ir for ME, I give them a buck or two. If they go to get it for ME, I give them a buck or two.