I seem to remember a similar anecdote where Steve Jobs told someone (Woz?) that he wasn’t too worried about other companies competing with Apple because their parking lots were empty on the weekends. This would have been in the ‘80s, probably.
If you give employees things to work on that are so interesting and potentially revolutionary that they’ll decide on their own to work on them as much as possible. That kind of organic enthusiasm might give you an edge over companies that don’t have it, yeah, and the parking lot metric isn’t a bad rule of thumb for finding startups that have truly engaged their employees.
But from her other comments it sounds like Mayer got it backward, and hoped that if she emulated the form, then the function would follow.