"Eliminating the distinction between the haves and the have nots is done exactly by limiting every man to one wife, even though they could afford several, and forcing involuntary celibacy on all teenagers even if they could safely afford a baby, or avoid conceiving it."

You seem to be conflating access to other resources with access to partners.

What used to be considered wealth is now considered below-poverty and malnutrition.

The environmental stressors are largely gone.

Social structures to keep consenting partners apart aren't really a part of any reproductive strategy which benefits anyone other than the guy with the knockout punch.

But we've always known that bullies try to get their way.

Artificially enforced monogamy and celibacy doesn't redistribute resources of any kind in the modern world.

There are still beta males and females so long as people can choose. And humans aren't lions. Large harems have been an odd idea that only occurred to a few cultures, and which seems to impede progress. Yet, so too does enforced monogamy.

Perhaps this is due to the fact that the structural requirements for punishing serial adultery tend to promote social inflexibility and information suppression.

The more open societies outcompete the closed ones and no-fault divorce becomes a condition for expansion.

Although it could be argued that the last greatest expansion of the underlying tools of progress was during The Enlightenment when capable teens were expected to behave like the adults that they are.

The links between genius and youth are certainly extremely strong in the arts and sciences. The truly revolutionary concepts occur to teens, and by the last stages of brain "maturity" in the mid-20s the math genius is largely played-out.

Perhaps the next great revolution that will provide the tools for the next stage will only emerge when we cease hobbling the innovators at the height of their powers.

And I seriously doubt that they can be fully participant adults ( as they once were ) while still being treated as children when it comes to sexuality.

Heck, the revolutions of the '60s are now largely thought of as for the best. And the whole shebang of civil-rights, the free-speech movement and the sexual revolution began in earnest when adult college students began to insist that the campus administrators not act in loco parentis to deny cohabitation.

Dante