Yes, incorporation is a crap piece of legal theory. It is provable that the purpose of the “privileges or immunities” clause of the 14th Amendment was to enumerate a Power to Congress to enact specific privileges or immunities that the several States could not disparage.
The “Privilieges and Immunities” that were common among all the several States when the Constitution was Ratified were to have been secured by A4:S2:C1 but, and here’s the rub, if a State did not fulfill the obligation to honor these the Congress could do nothing about it directly but had to wait patiently on the uncertainties of the Court, not just that suits would be brought but that the lawyers wouldn’t be nitwits and argue the wrong parts of the Law (as had in fact happened) and this lose their suit.
With the Ratification of the 14th and the “privileges or immunities” clause Congress no longer needed to wait on the Courts but had a recourse to act directly.
Moreover, the “privileges or immunities” that exist only because of federal statute may but need not bear resemblance to the Priviliges and Immunities that A4 addresses. Which is just to say that these aren’t a specific body of rights possessed among all the several States when the Constitution was ratified. They can be, and in fact all those in the first CRA were, but they need not be.
Still, and this is important, mere acts of Congress, statutes, can be removed by other acts of Congress, statutes. This would be distinct from needling an Amendment to remove some P&I.
As proof I would point you to the Slaughterhouse opinions and to the dissent of Justice Field. Why to a dissent?
Because in that dissent Field was laboring to argue why the butchers of NOLA should receive relief sought BUT he had to admit to the actual intended function of the “privileges or immunities” clause ... admit because it was then common knowledge and the water’s had not yet been muddied by writer’s speaking out of turn after Ratification, contradicting what those who had Ratified can be said to have agreed to (Hamilton did much the same when he spoke out of turn, contradicting after Ratification what he and others had told those with the Power to Ratify before they ratified). This I would qualify as a statement against interest, for it destroys the very point that Field had been trying to make.
The problem was that the nitwit lawyers for the butchers of NOLA had argued the wrong part of the Law, for they should have argued based on A4:S2:C1 and at least then they would have had a decent chance, one even Marshall would have possibly been open to had he still been around.
See here: http://www.freerepublic.com/focus/chat/3528726/posts
https://archive.org/details/DebatesThatLedToTheCreationOfTheFourteenthAmendment