Suppose a state passed a law saying that only married couples could have an abortion, this would then become a "legal incidence thereof" of marriage and nobody but married couples could constitutionally obtain abortions in that state.
A state could conceivably pass any law that is constitutional in their own state granting rights to married people and then any non married individual would be denied those rights. A poster in another blog suggested that cohabitation laws would become constitutional.
What if a state passed a law saying only married couples could raise children? On what grounds could this be overturned short of another amendment?
This amendment is screwed up in so many ways.