Unity was obliterated in the 60s by false doctrines with the perpetration of the NO and by the wolves who entered the Church and came out of hiding.
Vatican I clearly teaches that unity of faith is guaranteed by adherence to the See of Peter, something that R&R deny.
Nevertheless, there's unity and there's unity. Church history is replete with theological disputes among various schools. So a certain amount of contention is unavoidable, and might even be good in the long term, as the debate tends to clarify certain doctrinal matters.
But, to take the classic example of the Thomists vs. the Molinists, regarding predestination and free will, the debate continued, as the Church would not step in to take sides or to resolve it, yet the Church did forbid the two sides from denouncing one another as non-Catholic heretics for adopting the opposing position.
Among the various Traditional groups, we have many examples of disputed questions that are elevated to the level of certainty, resulting in the effective excommunication of those who do not agree with them ... such as, questions regarding the validity of the +Thuc line, the validity of NOM Holy Orders, the status of the NOM, the status of NO annulments, etc. Trad priests are not even pastors, much less do Trad bishops have jurisdiction. Their only role is to make the Sacraments available to the faithful on a emergency basis. So it's extreme over-reach for the various groups to refuse Sacraments to people who disagree with them. If I were a priest who, say, felt the +Thuc line was doubtful or that NOM annulments were bogus, I might advise the faithful that "It is my opinion that you are putting your souls at risk [in one of these areas]." But, that having been said, it would not be my place on impose this view on the consciences of others and refuse them the Sacraments on those grounds.
SSPV and some of their derivatives are particularly notorious for this kind of behavior.
Now, this does not mean that there aren't SOME questions that bear directly on Catholic faith that has in fact been decided by the Church, such as if there were "Trads" who rejected Vatican I or the legitimacy of Pope Pius IX (and consequently, papal infallibility and also the Immaculate Conception). But the vast majorit of these issues have not been adjudicated by the Church and so the Trad clergy have no authority to impose them on the faithful. Someone like a John Pontrello or Richard Ibranyi should in fact be refused the Sacraments as notorious manifest heretics.
You also have the SSPX who have traditionally tried to impose strict obligations of "obedience" both on the part of the priests and the faithful, excoriating priests who, say, leave the SSPX, as guilty of disobediece. Yet they have no actual authority that could bind them to obedience, and this is dangerously close to schismatic to pretend that they have an authority structure outside of and in opposition to the Church. So it's OK for them to disobey the Vicar of Christ, but not OK for a priest to disobey an SSPX "superior" who has no actual authority?