The other stuff though, like the hyper-inflation of the remainder of the tenets of "Immaculate" they do hold ownership of. I won't argue that. It took a few centuries to become fully fleshed out.
The idea of the Immaculate Conception went much further bad than that. John Duns Scotus was a champion of it and provided an argument that was used almost exactly by Pius IX five hundred years alter when he proclaimed the dogma. It is corollary to the doctrine of the Virgin Birth.