Because of the Fedgov's overbearing control of our "general welfare", "privacy", "interstate commerce", "taxing authority". These are all doctrines of our two party national federal supremacy war over matters relegated to states by the constitution. You argue with yourself on this matter.
Again - the argument that all children in america should have their lives protected - is not a state issue. The true nature of personhood isn’t a state issue either.
There are areas where states rights can and should prevail. This is not one of them.