Every oppressive regime, which can flourish only by ever greater measures to suppress human freedom, contrives loyalty tests and advances its agenda only by doubling down on strictures which ensure uniformity. True human freedom always stands as the mortal enemy of all inhuman regimes.
Vatican II-ism is a disease which demands everything be modernized and constantly changed to conform to ever-changing volition of whatever persons happen to be in power. Authentic service of humans and free will is lost.
The mortal sin of suppressing the sacred in search of a uniformity based on unilateral will to power is rumored to be forthcoming in a new power grab by overreaching curial officials in Rome. If it comes to pass it will violate canon law which decrees that no priest can be forced to concelebrate, the greatest goal of Vatican II-istic liturgy. Less Masses and more conformity. The principal celebrant decides how all the other priests celebrate.
Demanding that every priest also celebrate the Vatican II liturgy, as it is rumored the new document will command, is a petty loyalty test which reveals the increasing awareness of the fragile condition of Vatican II innovations, and their ever more tenuous standing among that ever-decreasing number of sincere Catholics who still practice the integral Faith, on the part of those who still cling to them. Such remains the purpose of existence for many who want to claim the ancient Faith without submitting to all of its obligatory commands.
Here we see that even a heretic, Karl Rahner, understood it is a sin to suppress authentic liturgical freedom and enforce uniformity out of a will to power:
(Herder, 1965, pp. 394-395)