No, C is not pointless, it's the most important part. Maybe you don't understand. You can't just edit a document that isn't the supreme law of the land to say it is an expect people to listen. It has to be given that status by the authority presently holding it.
The Powers of the Senate constitutional amendment and the Supremacy of Federal Law and the Constitution amendment refute your point quite easily.
The only valid argument presented is whether these amendments apply to previous legislation, since we had a Supreme Court case before the amendments which declared pretty much every law unconstitutional then because of the lack of the these two amendments above.
Follow?