Did you miss the part where I mentioned that I was involved in the hiring process (interviewing candidates both phone screens and in person) and the anecdotal statistics of postgraduate degree holders in the company over a non trivial amount of time? I am basing my claim on actual experience as opposed to "feelings" which you seem to be following.

People involved in hiring at these companies put almost no weight in if you have a post graduate degree when hiring SDEs. Most of the weight is put in the interviews, they'll interview almost anyone esp Facebook, Google and Amazon. They hire at such a high volume that they don't have the luxury of targeting post-grads.