We're talking about legal rights - as in, the right to visit a dying partner in hospital, or to employee benefits as a dependent.
And - other than blind bigotry - what's the big argument against? "We understand that when everyone can marry, no one can marry. There is simply no marriage left."
Here's a parallel statement: "We understand that when everyone can vote, no one can vote. There is simply no voting left."
That an otherwise solid conservative political platform contains so rotten a plank is shameful.