Hmm. When I joined Google, I interviewed the managers of both teams I was offered a position on, and a team member on the one I ultimately decided to join.
I'm not sure if this is the norm--I believe it differs for industry hires versus those fresh out of school--but it's certainly not true that, as a rule, you can never meet potential teammates.
Two decades in the valley has taught me that you can't decide anything in a half hour conversation beyond recognizing an absolute bozo incarnate. You need to meet the whole team and preferably have lunch with them and figure out whether it's the right next step. What Google does instead reeks of magical thinking to me.
Because for the most part, Googlers aren't bozos (although a couple of the true believers in the Googleplex blew my mind with how crufty their skills and knowledge had become), but that doesn't rule out one of the many great engineers there promoted to their managerial level of incompetence. And that's what I had - a guy with no people skills whatsoever - and two teams with a total of 20+ engineers to "manage."
I'm not sure if this is the norm--I believe it differs for industry hires versus those fresh out of school--but it's certainly not true that, as a rule, you can never meet potential teammates.