I see your point about getting government out of marriage.
However, with various aspects of family law, and administering matters such as Social Security survivor’s benefits, health insurance plans by employers, child custody, and others, marital status makes a difference.
And if marital status makes a difference, then government, at some level, must have a definition of what marriage is. I think it might be difficult to just do away with marriage as a legal matter.
I will not be getting married in government sanctioned union.
I will create my own agreement with terms and conditions mutually agreed to and the government won’t be informed.