The argument in favor of same sex “marriage” that originates in the observation that traditional heterosexual marriage is in bad shape needs to go into oblivion where it belongs.
The debater who appeals to this argument should be embarrassed by the degree to which he displays an utter lack of principle.
How so? Imagine his answer if he was asked, “So, if traditional marriage had a near zero divorce rate, the legitimacy of homosexual ‘marriage’ would be therby diminished?”
It’s not hard to imagine the immediate protest, “Of course not!”
“Oh, so you admit that your argument neither stands nor falls on the divorce rate? Then why use that in the first place?”
The charitable interpretation is that this is simply the product of a sloppy, undisciplined mind engaging in unexamined groupthink.
The less charitable interpretation is that this is not really meant as argumentation as such, but it is rather a shaming tactic in order to attempt to shut up the opposition and avoid anything resembling a principled debate.
Anyone appealing to this bogus argument is the one who ought to feel shame. They need to go away and do the hard work of thinking before they re-enter the realm of respectable debate.