I disagree, I think that there are a lot of developers that produce a constant stream of mediocre designs, mediocre implementations, mediocre testing and medioc

I disagree, I think that there are a lot of developers that produce a constant stream of mediocre designs, mediocre implementations, mediocre testing and mediocre documentation. And when a (let's call it 10x) developer steps in and produces just a very good design or implementation, it still adds a lot of value, to the project or to the team's productivity, even without tests or documentation. (In that sense, the 10x label is a misnomer: exceptional developers aren't faster at typing, they produce something that the others wouldn't produce in any amount of time, and that something often increases everybody else's productivity).