On this I half agree. If we stand on the shoulders of giants we still need to be looking in the right direction. It is unhelpful to stand on the shoulders of giants and be looking in the wrong direction. What we need is a long faithfulness in the right direction.
You may be surprised that I am a proponent of 'ecclesia semper reformanda'. And that the Catholic Church is actually for it too. The issue for me is whether changes are made with a hermenutic of rupture or one of continuity. Any reform contains a bit of rupture. That is inherent. But it should be a reform that points us back to a particular trajectory we were already on. And this is how it has to differ from Kuhn's 'Structure of Scientific Revolutions'. For in science we delve into unknowns at every turn and we operate on guesses until better guesses come along. The faith differs in that we have Jesus teaching his disciples, choosing apostles who would teach their successors who would teach their successors. While not everything is figured out, everything that the apostles knew was golden. Everything their early successors knew was argent. So we want to see where they stood and see who stood on their shoulders and where they stood. The term for that is 'ressourcement' and it is a going back to sources in the Bible and the Church Fathers. It can be done with a hermeneutic of continuity allowing the Church to reform, to stand on the shoulders of giants, and to look around but point in the right direction again.
The contemporary best well known example of this way of thinking is pope emeritus Benedict XVI. He didn't dump the past. But he wasn't static either. He went back to earlier sources, and we know those sources were on track because we know Jesus was on track. Not everything, especially the newest things, are on track. Particularly it is the newest things where time has not tested them, where we will need to change, to get back on track. It's only after a few hundred years that things even begin to clarify.
What does this have to do with Mary? The idea that Mary was a sinner is actually a new idea. We should look carefully at the Fathers to see what they thought of it. In that we might see how we got to where we are. The Orthodox have similar ideas about Mary though they would be unhappy to actually agree with Catholics. What is the common ground? What are their sources? Does that all make sense? What is the entire history? Are current ideas in concert with the older ones, the oldest ones, or a rupture?