Article V
The Congress, whenever two thirds of both houses shall deem it necessary, shall propose amendments to this Constitution, or, on the application of the legislatures of two thirds of the several states, shall call a convention for proposing amendments, which, in either case, shall be valid to all intents and purposes, as part of this Constitution, when ratified by the legislatures of three fourths of the several states, or by conventions in three fourths thereof, as the one or the other mode of ratification may be proposed by the Congress;...which, in either case, shall be valid to all intents and purposes, as part of this Constitution
The point that seems to be going over your big-font head is that certain amendments if added would change the principles of the Constitution away from the intent of the Framers.
Heck, we could add Amendments to the Constitution straight out of the Communist manifesto, but of course that would change the principles of the Constitution.
You get, yet?