and...that's amusing

I've spent half the day defending polygamy in an "idealized" ethical construct. For the most part the arguments against are very similar to those raised by people opposed to homosexuals marrying or, before that interracial marriages. "It's for the children!" Think of the children. To quote an old now dead comedian, "Fuck the children". We don't require people to prove they're having kids when they get married, or to be married to have and raise their children (or even anybody's at all). Don't see the point in arguing against this on this basis. More over, practically anybody can adopt. And then enter into any kind of private sexual relationships with other people that they want and still retain custody of the child. I don't see why they should have to lie and say, yes, this is my (husband/wife) to get that out of the way either and still be capable of raising a child.

There are a couple very important caveats of course that I raised before when this comes up in the war over ethics and law between oddballs like me who tolerate a lot of random behavior and traditionalists who don't.
1) Polyamory is typically practiced in its non-idealized fashions. That is: by men asserting dominion over women for selfish ends and sexual exclusivity with many women

2), often without consent or even knowledge from each individual party to these sexual congresses. (it is not required that such things involve multiple marriages, though in practice, that'd probably be more convenient for people who want to do carry it out).

I'd have to say I agree this reflects rather poorly on the practice in modern times. It should really only be ethically permitted where all parties have agreement and consent and there's a level of transparency and accountability as in any sexual relationship, and, ideally, there's an equal access such that the practice is not simply used to effectively own women but that women could have multiple partners themselves if they wish (polyandry). Since that doesn't typically happen either, it's probably a dead issue but for the fact that we have many examples of marital infidelities to deal with in some manner.

I'd say we might benefit if such people who had these demands were open about it and perhaps did not get married or only married people who were "okay" with such things. I also don't think the population of people who would find this acceptable behavior, certainly during these supposedly essential child-rearing years, would be very high at all. But without permitting such a population to exist openly at all, we're essentially fostering a cynical violation of the supposed value of monogamy by entreating people to abuse it privately and illicitly rather than privately allowing people to discriminate with full knowledge of the consequences of entering into relationships with such people. (Ie: they could avoid some potential damage).