A society with high sexual competition or a society where the sexual market is as free as possible wouldn't result in a lot of benefits for most people because :

(1) It would decrease the number of intelligent people in society as Jocks would be vastly more successful in impregnating women through casual ssxual encounters. No more needs in society.

Intelligence is already a highly dysgenic trait and intelligent, educated people reproduce far less in Western liberal countries.

(2) It wouldn't actually create superhumans because there are genetic tradeoffs being involved. You are trading one set of genes for another set of genes. At least for a few hundred generations.

(3) It won't lead to faster biological evolution in humans because of (2) and because biological evolution is very very slow whereas we now currently rely on cultural evolution and evolution of knowledge.

(4) It would result in a highly unstable society as Polygamies will be rampant and tons of cases of single motherhood will result in a society having a very high number of single men, who are probably virgins even in their primes.

(5) It would worsen the effects of economic inequality because of (4). Now wealthy people would be free to have harems like emperors.

This gives very little incentives for rest of the males to participate in the system, they will either revolt and cause revolutions or they will simply leave and go rogue.

(6) It would result in a lot of inbreeding too because of the Polygamy involved.

(7) It will be a highly R selected society and people would keep on having more and more children instead of investing in the children that they already have. No more K selected society as children are now disposable.

This would result in a society where nobody invests a lot of resources as they may lose their assets easily because of (4) and social/class heirerchies keep on changing very rapidly, thus making inheritances an unreliable strategy to successfully pass on your lineages.

(7) If you want to reduce genetic diseases or have a healthier population then genetic engineering is a far more reliable option.

(8) It would result in a society suffering from rampant Sexual Hedonism and where people are addicted in dopamine loops. Thus is very unhealthy for the Brain and has other associated risks too.

(9) The (8) will result in a society where people, especially men are without any strong motivation to innovate or improve themselves as they can easily have access to sex.

(10) This would result in a society where blood relations are not important, children don't look after their parents in their old age, social trust decreases, parents don't give any heritage/heirlooms to their children nor expose them to any culture, resulting in identity crisis and there is no such thing as an extended families.

Nobody would have any idea which distant relative they are having sex with and this will result in a lot of accidental incests.