What this whole thread's argument is really about is a bunch of people with libertarian political philosophies wishing the government in the U.S. didn't wrap so manylegal rights, tax status, and frankly … life legal standing ... up with marriage itself, thus making a marriage license itself a legal license.
Unfortunately, it does. You're actually asking for a whole lot more that's way tougher to get done and change by saying you want government out of the business of marriage, period, than you would be if you just acknowledged reality as reality and simply asked to be treated the same as a heterosexual pairing and gain that legal word -- "marriage."
It was the path of least resistance, and honestly, there are few enough people on a cultural level in the U.S. to make your anti-government-involved-in-your-married-status stance a viewpoing of a clear minority. It might thrill you to your core when you talk about shrinking government, and it might make you tremble in excitement when you envision a world in which Uncle Sam is less of a presence in your lives .... but still, acknowledge reality and understand that you could pull 100 people in the country at random and teleport them into your living room right now, poll them all, and you're almost guaranteed to be in a CLEAR MINORITY with those viewpoints. Most people like the fact that marriage licenses are a thing. In a democratic republic, that means your deepest desires for the exact approach about how this thing would happen is probably NOT going to happen.
This whole argument boils down to a moot point about a hypothetical country that exists in another universe -- it's also a moot point now because we've already won the battle, it's the law of the land, and it's a done freakin' deal. We did it the easiest, most rapid way possible for us, and it was a giant stride towards equality. I wasn't about to wait for six more decades for a glorious Libertarian revolution to gain momentum so you types could have your cake and eat it too.
Why are we still talking about it?