Just because you saw a few exception does not mean the rule does not hold in general. Or are you saying most people don't learn with time (a corollary of your theory that age is not a big factor)?
A have met people much smarter than me who wrote bad code because they were working from a theoretical framework which just didn't correspond to realty.
Programmers by the nature of the profession must be good at learning over time... and I find it difficult to believe someone who is good at learning when at 20, will be bad at learning when at 40...
> some get more out of one year's worth of learning than others get in 10.
Sure, but they probably continue learning the year after?? And the year after??? Or they too, stop learning (or are just too rare)?
I think this is correct. The curve flattens with age (in my opinion).
> you saw a few exception
I think the seniors you met (the knowledgeable ones) /were/ the exceptions. Most seniors I have seen have convinced themselves that they know all there is to know.
Yeah, seems we've met different kinds of seniors... I don't know any senior who wouldn't understand that "the more you know, the more you understand just how much you still don't know".
So, combining the winnowing of the not-very-apt with the gaining of knowledge through experience, the end result is that you have a preponderance of wise old experienced contributors.
I you are one of the younger inexperienced ones who believe they know better it's likely you'll self-select at some point, secure in your Dunning-Kreuger knowledge, and move to some career in which your high level of competence is valued more.