1) Project/Field 2) Name brand recognition
The game industry has a lot of overqualified people on very poor salaries in poor conditions because games are sexy. Google has both sexy projects and name brand recognition, which allows them to recruit top level talent despite the fact that their interview process is absurd and frankly, pretty insulting to qualified professionals (can you imagine doctors or lawyers going through similar processes?). Reason being, having google on your resume opens a lot of doors, and there's a chance you get to work on something really cool.
So I don't know anyone that works at Netflix, but I would believe they have mostly above average engineers not because of this bizarre practice of firing "average" people, but because they have enough recognition to find above average people in the first place.