So for example Google, Facebook, Microsoft, are all deluding themselves? Would they be not any worse off if they replaced interviews with say rolling dice?
I'm not saying that (eg) Google has a better option than conventional interviews; Google has unique hiring problems. That doesn't make the interview system they use better. (Also, I don't have great intel on how Google interviews work; nothing better than you have. Maybe they've solved this problem in other ways... though, I'm skeptical.)
Startups, though, have no excuse.
It's an interesting question whether a random sampling of Google engineers would outperform a random sampling of tech industry product developers from other companies. I don't know.
The bigger is, within the broad set of candidates that an interview process selects for, the conventional job interview is arbitrary bordering on capricious; it's inhumane for no business benefit.