Yes, the phrase "it's all about the children" applies to the marriage contract. If you are married and don't have kids, that doesn't change the contractual terms of marriages in which children do arrive. The few do not set the terms for the many. And in most married homes, children arrive.
Here is the thing- neither Obergefell or Windsor had children.
Yet you say they should not have been allowed to marry.
Because of the children. That they don't have.
Yet you say that two 80 year old heterosexuals should be able to marry- even though they will never have children- because marriage rules are not defined by exceptions.
Why do you think that two 80 year old heterosexuals should be able to legally marry- but not two 80 year old homosexuals?