Well, just who is correctly upholding the values of Catholic teaching is the issue. Traditionalists ascertain which V2 and modern teachings are valid based upon their judgment of what historical (from so-called church "fathers" and medieval church teachings to Pius V) say, while they condemn us for doing the same (since our source is the only wholly inspired record of what the NT church believed, in contrast to Catholicism), and thus modern RCs call the Traditionalists "Protestants." And btwn the two are groups in various degrees of separation.
Broadly speaking, both tell us we need their magisterium as a remedy for our divisions, though we traditional evangelicals are the most unified major group in core conservative beliefs, yet as one poster wryly stated,
The last time the church imposed its judgment in an authoritative manner on "areas of legitimate disagreement," the conservative Catholics became the Sedevacantists and the Society of St. Pius X, the moderate Catholics became the conservatives, the liberal Catholics became the moderates, and the folks who were excommunicated, silenced, refused Catholic burial, etc. became the liberals. The event that brought this shift was Vatican II; conservatives then couldn't handle having to actually obey the church on matters they were uncomfortable with, so they left. ” Nathan, http://www.ratzingerfanclub.com/blog/2005/05/fr-michael-orsi-on-different-levels-of.html