In my post The Problem with Polyamory, I opined that polyamory, the state or norm of having several partners, as well as dating apps and dating sites, make the human mating market more efficient. This is generally the case for sexual permissiveness.
This means that the political Left is against letting the invisible hand of the market work out the economic fate of people, but in favor of letting the invisible hand of the market work out the sexual fate of people, while for conservatives it’s the other way round.
Economic capitalism has the proven advantage of enabling unprecedented economic growth by aligning incentives for innovation and human nature. Similarly, we can expect sexual capitalism to improve partners and partnerships. For example, I assume that the current high rate of extremely fit people has a lot to do with sexual market pressures and opportunities.
Unfortunately for the Leftist standpoint there is a big difference between goods and partners.
Goods can be improved in quality and availability almost indefinitely. The possibility to innovate does not easily run out. A long history of economic growth can attest to that. That is the reason why we put up with the significant downsides of economic capitalism.
Partners on the other hand are limited by human nature. At least so far. There is no rising tide that eventually lifts all boats. Instead sexual capitalism just like economic capitalism leads to people winning big and people losing big. Without the redeeming feature that in the long run, even the losers of the future will be better off than the winners of the past.