In response to the sad occasion of blogger Bill Cork leaving the Catholic Church, Zippy Catholic points out:
A Catholic submits to Peter knowing full well - or at least responsible for knowing full well - that Peter hasn't promised, when it comes to a great many things, not to change his mind. A Catholic submits to Peter because Peter is the Vicar of Christ, given the keys by Christ.
And as a commenter points out:
You can't avoid obeying a fallible human, because even if you reject everyone else's opinion and do what seems right to you, you are simply another one of those fallible humans.
So, the question becomes, given that I have no choice but to follow the opinion of a fallible human, has God selected any particular fallible human for me obey in certain matters?
I think that not understanding this is a serious problem for many. Progressives and Radical Traditionalists both make such a mistake. I can't tell you how often I see people say, "You used to say X (which was good or bad) and now you say Y (which is bad or good) violating non-contradiction standards and thus either you were the true church and have ceased to be so, or you never were and never will be.