Thing about Catholic theology is that it’s not self-evident. You can explain all you want; you can proclaim it from the rooftops. But you’re not going to convince anybody unless you can convince them that the source of your authority is valid.
Indeed, for Rome has presumed to infallibly declare she is and will be perpetually infallible whenever she speaks in accordance with her infallibly defined (scope and subject-based) formula, which renders her declaration that she is infallible, to be infallible, as well as all else she accordingly declares.
"Private judgment" as in ascertaining the veracity of church teaching by examination of ancient church teaching (the NT) is thus censured as being fallible and divisive, and looking to the pope and magisterium is called for instead. Even though traditionalists ascertain the veracity of church teaching by examination of ancient church teaching in dissenting from the pope and magisterium, except their standard is mainly extra-Scriptural historical Catholic writings.
Yet despite private judgment being impugned as fallible and divisive, it is sanctioned if and as the means of bringing to forsake it in ascertaining the veracity of Catholic Truth claims.
...having discovered the authority established by God, you must submit to it at once. There is no need of further search for the doctrines contained in the Christian Gospel, for the Church brings them all with her and will teach you them all. You have sought for the Teacher sent by God, and you have secured him; what need of further speculation? Your private judgment has led you into the Palace of Truth, and it leaves you there, for its task is done; the mind is at rest, the soul is satisfied, the whole being reposes in the enjoyment of Truth itself, who can neither deceive nor be deceived....”
“All that we do [as must be patent enough now] is to submit our judgment and conform our beliefs to the authority Almighty God has set up on earth to teach us; this, and nothing else.” “Absolute, immediate, and unfaltering submission to the teaching of God's Church on matters of faith and morals-----this is what all must give..” —“Henry G. Graham, "What Faith Really Means", (Nihil Obstat:C. SCHUT, S. T.D., Censor Deputatus, Imprimatur: EDM. CANONICUS SURMONT, D.D.,Vicarius Generalis. WESTMONASTERII, Die 30 Septembris, 1914 ); http://www.catholictradition.org/Tradition/faith2-10.htm]