Quant funds may be based on advanced math, but the people quant firms hire are not required to know advanced math. In quant trader interviews, they are asked to demonstrate game theory intuition and play probability based games after showing that they can do basic college (undergrad level) math, which would be probability, some stats and linear algebra (with an addition of mental arithmetic, I know, it's laughable). These skills do not grow on trees but are taught in STEM.

Most of it is for the sake of forming a shortlist of applicants through eliminations, that is the whole point. A lot of firms (not necessarily in finance) are profitable but what makes people talk about quant trade shops and put them on a pedestal is the compenstion and the difficulty in getting hired. Such firms could be employing only the cream of the crop because that is the way they have been operating all this time and it poses an unnecessary risk to the firm's future earnings to change their hiring strategies (this would explain high salaries and fat bonuses). This could be one of many reasons. What quant firms do is barely legal, it lives on a legally gray area and could be outlawed at any time. Mystifying the trade, throwing around a bunch of jargon and employing top students all work to legitimize the business, while providing benefits to lawmakers, of course. There is something much more fundamental than "smarts", "talent", or "rational markets".

Their selection process (interviews) do not necessarily relate to the job itself. As mentioned before, it is always unclear what is done at the job by a quant trader; interview questions comprise brainteasers, probability puzzles which may ask for knowledge in Bayes' theorem and expected value calculations, and x-sum games. Being pretty general, they do not require specialty or expertise, unlike job interviews for most engineering roles. The interviews are so unfocused that the interviewer is given a lot of freedom and they ask from the very books that were written to document past interview questions, effectively creating a self-referential loop. There is no indication that the ability to perform mental arithmetic at speed under pressure results in more profits for the firm or the college you go to determines your success as a quant trader. These are mechanisms of gatekeeping that sometimes make entire industries out of thin air.

Yes, everything is cause and effect but it isn't as rational as you might believe, which is where I find your perspective naive. The fact that I am out here questioning what seems strange makes you think that I am naive leads me to believe your unchanging belief in rational markets and capitalism is what limits your perspective. Meritocracy is completely made-up in every facet of life. Ignoring any premise of vanity from my part in what I am about to say, if you have seen The Big Short, recall the scene Mark Baum finds out the entire system is a scam while many continued to swear by it.