The conflation of True Church and Catholic Chruch needs addressing. The One True Church is made up of ALL BELIVERS since the day of Pentecost when The Holy Spirit began indwelling believers. The Roman Catholic Church is a sham designed to use Christ to empower a hierarchy of men spouting traditions.
All I’m saying is that Roman Catholicism (traditionally) does equate itself in totality with the True Church. But IF (and this is an important IF) it is going to do that, then they must -at some level - be infallible in determining dogma and doctrine. If not, then at any point (including the early history of the Church), fallible men could pervert the teachings of Christ without repercussion from God and lead all future generations’s of men and women astray with false doctrine.
To put it another way, would Christians of all modern denominations say that God spoke to the Apostles and Early Church Fathers, but they all largely chose to ignore God AND God simply permitted them to ignore him without “righting the ship”’. It’s unthinkable if we are to maintain the integrity of teachings going back to Christ. Furthermore, it seems incomparable with God’s Providence to hold that only a small group of people through time have taught “True Christianity”, while the vast majority of those wishing to be Christians have practiced falsehood.