Certainly! It's one of the primary reasons. Show me one gay couple that that does have sex. Just one. Without sex they aren't married, they are best friends. Now, if you are suggesting that best friends get married because they want certain benefits that accrue only to married couples, like getting on a superior insurance program, or accessing government benefits, that's not marriage. That's actually fraud.
No it's not. They can have sex anytime. We're not talking fundamentalists who can't do the deed until they take their vows.
Ahhhhh! How wise of you.
So they don't really need to get married at all. There is no particular liberty associated with marriage. They just want some mythological sense of equality and have their relationships given the same recognition and respect as traditional marriage. Except they don't have a good reason for it, other than to make themselves feel good. It's all about them feeling good about themselves. Same sex relationships are the foundation of nothing, build nothing and don't benefit society whatsoever. All they can do is reduce the general marital institution to one of depravity.
It's the same arguments that legalizing drugs and prostitution is best for the culture. All it does is make them feel better about what they are doiing. Reducing the age of consent for sex to 6 isn't to help children feel loved, it's to make pedophiles feel better about themselves. Getting divorced 6 times doesn't build families, it makes the serial polygamist feel less guilty. Change behavior and belief justifying the behavior will eventually follow.
It's all about depravity and degeracy. The more people degenerate the better and the more normal degenerates feel.