3 is a odd number

Pete Wells has an interesting discussion on the concept of "small plates" over at the NYT (The Big Problem with Small Plates). Over the last year or so, we've noticed quite an increase in the number of places in Richmond that have hopped on to this trend.
Some places around do small plates better than others, but typically it does appear that the amounts served, coupled with the prices charged dont often make this a workable concept for the diner(s).
So is this an issue of supply-side economics or does "plate sharing" indeed drive traffic positively?

I like the solution in many parts of Spain -not only are the tapas/pintxos of reasonable size but they also can come with an option of a raciones which is larger and meant to be shared by larger groups.

Blog title comes from the pedantic mathematical conundrum of having to share 3 items on a small plate - 3 scallops, 3 slices of bread etc! I love 3s (trifectas, triumvirates, trinities and all) but does this help any but groups of 3x ?