You cannot back door constitutional amendments through acts of congress.
A literal reading of your above sentence is in direct contradiction to Article V
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........
The Constitution, via Article V, says specifically that acts of congress when passed by 2/3rds of both houses and ratified by the legislatures of 3/4ths of the states "shall be valid to all intents and purposes, as part of the constitution."
So constitutional amendments via acts of Congress is one of the methods specifically enumerated as a means of modifying the Constitution and is directly contradictory to your assertion. This was the case of the 14th Amendment and is why USC title 8 section 1401 subsection (a) exists.