It sounds to me less like a money grab, and more like an attempt to discourage large groups.
If you've ever sat down and dealt with a waitress in a group of 8 people or more, you'd know that it is way harder for them. It's harder for them to keep track of who ordered what, it's louder for other patrons. And, it seems to be more likely for the kitchen to miss something in the order when trying to coordinate the arrival of 8 plates at once.
Add to that the fact that people usually want the tab split up, and people seem to be more willing to short on the tip, assuming others will cover it.
I'd attempt to discourage it too, or at least to make sure it's worth the headache. On a normal day, it's probably not a big issue, but, with the Olympics in town, they probably realized right away that it could be a chronic issue causing constant headache as people move tables around and talk to someone 6 people over at the top of their lungs.