It is silly only in post modernism. Marriage is the necessary union of a male and a female to secure the good of offspring. Sex is part of marriage. The reason for marriage having a public element is that it produces a family. Friendships don’t need a registry or a ceremony.
The Holy Family is a special case because Jesus needed a human step father to care for Him and His mother.
Many men who want to commit homosexual acts, or now commit them exclusively, do have children. But the union of two men itself can never produce children. It is, by nature, a parasitic, narcissistic union.
It would be better for a homosexual to only commit his acts with one man rather than many. But that lesser evil doesn’t make the homosexual household suddenly a good thing. It is a terribly evil thing. I can’t say it is never better that a child be raised by two homosexuals. Certainly circumstances could be otherwise so awful for this child it would be better. But that doesn’t mean society should recognize the relationship.