It is a conceit to assert that homosexual people 'have sex'; I guess that means sexual intercourse within their sex.
Not so; sexual intercourse has the potential to produce a zygote.
Homosexual people stimulating each other's genitals is not sexual intercourse (of course) because there is no chance of a zygote. Thus, it is just a parody of sexual intercourse (sex being about reproductive difference).
So people who don't have sex want to get married...how odd.