I've yet to see open source code from FAANG or other big players that looks like it was done by a genius. it's just professionals who know how to read documentations, and know how to write clean code and know how to work in a good engineering process.
also when you're building an app (web, mobile, SAAS ...) I really really doubt you need or want 'extraordinary' people ..
Then you add on top of that, companies tend to give pretty strong incentives to do their work anyway (you know, survival and luxuries). Even "cash-strapped" ones tend to pay well over median.
I'm skeptical of what Microsoft considers an "average contributor" considering they were known to have a pretty high bar for recruiting (they were notorious for rigorous algorithmic interviews even back in the 90's). And the comp was also pretty strong especially considering stock performance back then.
[0] https://www.joelonsoftware.com/2006/10/25/the-guerrilla-guid...
Extraordinary people are extremely limited. The recruitment process is not perfect. The performance equation consists of far more than just the individual's capabilities. Every variable is subject to diminishing returns upon investment.
Microsoft study aside (I couldn't find it either, mostly redirects to Teams), there are tons of studies coming out over and over pointing out how capable the ordinary person is when put in the right environment. We see this every day too, a complete "nobody" rises to fame within a year of dedicated work, to levels most people would claim "you need 5-10 years to be at that level", if not more. And these people aren't doing it in unimpressive ways like making a meme game or a joke website or whatever, no; they are making things which put companies with millions of dollars in budget to shame. If individuals can do this on their own accord, so too can a team with a specialist open to teach others, in work far less glamorous and difficult.