Well, maybe. But here’s the thing, what you propose can work for a generation or two, but relationships are how our species creates a stable future. The data about children raised by single mothers, especially boys, is not great. Failure to thrive isn’t self-perpetuating on a massive scale. And we’re already seeing lots of women who simply give up on the marriage scene. Why aren’t they already participating in polyamory? Some undoubtedly are, but enough to change society? Not sure about that. There a lot of things about monogamy that suck but it works for lots of people over long time frames. The other thing to consider is finances. Having a family and raising kids is expensive and doesn’t leave much for dating over the period of life when you are most sexually active. So we need a structure that accounts for enough stability to raise kids. Polygony is one possibility but it is illegal. This could happen in open marriages, which is where I think you’re heading. But I think it’s hard to square this circle.