I've always hated this term and the mindset around it. I think organizational practices, intelligent engineering strategy, etc are far more important to the output of a team than hiring one genius dev.
Like when my old work actually started measuring ticket closure times, our best developers were only 2x more productive than our worst ones. But suddenly a lot more tickets were getting closed.
I mean,I know that some complicated tasks needed the best developers, as the worst ones literally were incapable of understanding the code, but then again doesn't that say something about the code itself and how poorly it communicates its intent? Perhaps clever code is simply confusing code...
Those organizational practices and strategy make the best developers better.
If you hire shitty/unqualified developers who cannot communicate, don't know the tools and aren't functional, even the most amazing developer is kneecapped from a productivity point of view because she must be accountable for everything, forever -- the idiots drag her down.
It's like anything else -- if you work at McDonald's, a bunch of slow unmotivated workers will slow down a fast/hard worker. It's just that the value of the labor + output for cheeseburgers is much lower than software!