A fair part of the abnormal productivity of (for example) Einstein & von Neumann is probably down to when they were born.

To have a hope in hell of being the Greatest Of All Time, a scientist has to work in a scientific culture with (1) a supply of big & solvable open problems to attack, (2) sensible earlier ideas & theories on which to build, and often also (3) good enough technology to collect evidence that might confirm new theories. But it follows that a scientist doesn't have a chance of being the GOAT unless they're born at the right time. If they're born too early they end up like, say, Aristotle, someone impressive and historically important but nonetheless long superseded; if they're born too late, most of the prestigious solvable problems will have been picked off by someone else, and even if the scientist picks one off themselves, they're still trying to stand out in a more crowded field.

If Einstein had been born in 1500, or 1950, he might've been a Galileo or a Copernicus, or a Bekenstein or a Perlmutter, but he wouldn't've been an Einstein.

Of course this can't the whole explanation for why scientists differ so much in productivity, because you still have big differences in productivity even within a cohort of scientists all the same age. Nonetheless, if we want to explain why we're talking about Einstein instead of e.g. John Archibald Wheeler, the fact that Einstein was in the right time and the right place probably has a lot to do with it. While I agree that part of the reason for von Neumann & Einstein's vast productivity is the nonlinearity of the ability-productivity relationship, I think it's worth bearing in mind the right-time-right-place effect as well. (Knowing about that effect also makes Yudkowsky's brain-line diagram less surprising.)