> Except that a Google employee moving to someplace with a weaker economy has not reduced their leverage. These are people who have the power to simply move back.

A Google employee that moves away both changes the pool of options that employee has (only companies that offer remote or local ones in his new place of living - versus companies in (SF, NY, whatever)), and the alternative options that the employer has (he is now being compared against a much larger pool of people who can work remotely). That is indeed decreasing leverage.