Neither of those points invalidate the idea presented.

Just because it's not a uniform distribution doesn't mean the average changes. Most people learning a thing earlier in life doesn't change the average rate. Even if literally every single person learned a given fact on their ninth birthday, that still averages out to the same rate.

As for your second point, you're conflating "things everyone knows" with "knowing everything". Obviously people who are 80 still don't know everything, but it's not unreasonable to assume they share a pool of common knowledge most of which was accumulated in their early life.

And even if both of those things were valid criticisms, the thing you're calling out as "inaccurate pseudoscience" is the suggestion that people shouldn't be ridiculed for not knowing things, rather we should enjoy the opportunity to share knowledge.