Worth a try.
It's not obvious to me that "universal learner" is a thing, as "universal Turing machine" is. I've never heard of a rigorous mathematical proof that it is (as we have for UTMs). Maybe I haven't been paying enough attention.
Even if it is a thing, knowing a fair number of humans, only a small fraction of them can possibly be "universal learners". I know people that will never understand decimal points as long as they live or how they might study, let alone calculus. Yet are not considered to be mentally abnormal.
The compelling argument to me is the evolutionary one.
Humans today have mental capabilities essentially identical to our ancestors of 20,000 years ago. If you want to be picky, say 3,000 years ago.
Which means we built civilizations, including our current one, pretty much immediately (on an evolutionary timescale) when the smartest of us became capable of doing so (I suspect the median human today isn't smart enough to do it even now).
We're analogous to the first amphibian that developed primitive lungs and was first to crawl up onto the beach to catch insects or eat eggs. Or the first dinosaur that developed primitive wings and used them to jump a little further than its competitors. Over evolutionary time later air-breathing creatures became immensely better at living on land, and birds developed that could soar for hours at a time.
From this viewpoint there's no reason to think our current intelligence is anywhere near any limits, or is greater than the absolute minimum necessary to develop a civilization at all. We are as-stupid-as-it-is-possible-to-be and still develop a civilization. Because the hominids that were one epsilon dumber than us, for millions of years, never did.
If being smarter helps our inclusive fitness (debatable now that civilization exists), our descendants can be expected to steadily become brighter. We know John von Neumann-level intelligence is possible without crippling social defects; we've no idea where any limits are (short of pure thermodynamics).
Given that civilization has already changed evolutionary pressures on humans, and things like genetic engineering can be expected to disrupt things further, probably that otherwise-natural course of evolution won't happen. But that doesn't change the fact that we're no smarter than the people who built the pyramids, who were themselves barely smart enough to build any civilization at all.
10% of things that vary in quality are obviously better than the other 90%.
Dead people are notably unproductive.
Sorry for being unclear. If everyone agreed about utility of one over the other, the airlines would enable/disable seat reclining accordingly. Everyone doesn't agree, so they haven't.
(Um, I seem to have revealed which side of this I'm on, indirectly.)
The problem is that people have different levels of utility from reclining, and different levels of disutility from being reclined upon.
If we all agreed that one was worse/better than the other, we wouldn't have this debate.
Or not to fly with them. Depending which side of this you're on.
For what it's worth, I think the answer is completely obvious, too, and have killer logical arguments proving that I'm right, which those who disagree with me must be willfully ignoring since they're so obvious.
The debate is whether the space occupied by a reclining seat "belongs" to the passenger in the seat, or the passenger behind the seat.
In all these debates (I've seen many), advocates for either view are certain the answer is (a) obvious and (b) corresponds with whatever they personally prefer. (b), presumably (and to be charitable), because everyone else must surely prefer whatever they prefer. Tall people tend to be sure the space obviously belongs to the passenger behind. People who can't sleep sitting upright think it's obvious the space belongs to the passenger in front.
The lack of introspection or understanding of how someone else could see it differently is what really amazes. Each viewpoint seems utterly obvious to its adherents - those who disagree must be either inconsiderate and selfish, or whining, entitled and oblivious that they enjoy the same rights as other passengers.
This seems like a model for many other disagreements of more import.
Why are we so blind to the equal weight of symmetrical opinions?
Why are we so blind to our bias toward rules that benefit ourselves over others?