You get FB enticing talent from google, and google giving raises to keep people and this makes all other companies at a disadvantage.
Further, paying college grads 100K+ sets them up to be prima donnas almost immediately.
Last, it is against the stance that when starting your own company, and taking on money, the VCs want you to take smaller salaries to show that you have skin in the game, that you're hungry etc... This makes it such that lifestyles become set and the likelihood of anyone willing to take less is not going to happen.
Over time - the overall market salary expectations increase, but now the available talent pool that is actually worth those salary levels shrinks - putting both talent and employers in a catch 22.
Every single entrepreneur in the valley should see Google, and even more, Facebook as nothing but their enemy (until they try to acquire you, that is)