We Traditional Catholics are in a much, much better situation now than in the 70s, 80s, 90s and early 2000s. Why? Because in the first 40 yrs after V2, we made the argument that we must stick with tradition and the True Mass because we had doubts about the novelities and liturgical sacrileges of new-Rome. Our argument was based on logic, yes, but it was not 100% defendable. We were following our conscience and prior examples of the saints in similar situations, but still, we did not have a concrete defense for rejecting new Rome.
All that changed with Benedict's "motu proprio" in 2007. In this legal docuмent, he settled the matter that we had all wondered about for 40 yrs - Did Paul VI overrule Quo Primum? Benedict said emphatically "Quo Primum was not abrogated". Therefore Quo Primum is law! Therefore the entire Traditionalist movement was vindicated as operating legally within the laws of the Church! Therefore, not only are we ALLOWED to say/attend the True Mass, a often overlooked part of this law is that we are all COMMANDED to ONLY say/attend the True mass and it's accompanying rites.
Therefore, as it is law today, any catholic is OBLIGED UNDER PAIN OF SIN to only attend the True Mass and if they do not, and attend any other form of liturgy (which liturgies are unlawful), they sin against Quo Primum, which is disobedience to the pope.
It's great to be a traditional catholic nowadays!