I suspect the reason for this is that even great engineers don't scale indefinitely: At some point, if you want to increase output, you have to delegate some part of your work. To increase output even further, you have to delegate even more. That also doesn't scale indefinitely, so you have to start delegating the delegating. And before you know it, you're an SVP and not really directly doing any technical work anymore.
In Amazon terms, great engineers “are right a lot”. That is key in SVP type roles. An SVP isn’t typically managing ICs, they have a very different role than the manager role described in Charity’s article.
