I think there are more than a few anectodes. This is not true for google but fb promotes engineers really fast from 3-5 and 6.

3-5 if you don't get promoted after a year and a half or something they mark your packet expectation is you go from 3-5 very quick on average and even faster at the tail.

I did 3-7 in 6 years at Google and it was the fastest in the larger org with >500 people. You can do 4.5 at fb easy.

And yes at fb 7 years would rack lots of engineers 1+ m, even assuming modest gains.

If you don't believe it, it's your choice but not all companies treat employees as average. Google optimizes for average, fb rewards high performers...