Most of our hires are not developers. We're not building cutting edge tech. We have some internal tools but I don't believe they require "top developers" by whatever metrics Facebook might use. That said, I think the few developers we have are exceptionally good - versatile, multi-skilled, quick learners, broad experience, the ability to conceive, manage and run a whole software project without very little help... and whatever they decide to develop, they do develop. As a developer myself, tech cofounder of my two previous startups, I rate them as excellent developers and would be happy to work with them on any project. One of them, with no academic credentials, is the smartest person I know.

Re: your second point, I don't believe in the concept of "B players". See http://danieltenner.com/2014/09/11/there-are-no-b-players/

I am sad that you see this as insulting. I'm not justifying anything. These developers (like others in the company) have largely chosen their own salaries. One of them is in the top pay bracket in the company. They also chose my salary, btw.