Instead of reading Fr. Zuhlsdorf’s “excellent” series of posts, I will look at the collectarium in my Monastic post-Conciliar Breviary (same collects as at the Mass) compared to Christian Prayer which also uses the same collects as at Mass.
In Advent: two mentions of “peccatis/peccata” in the collects. 1974 translation uses the word “sin” in both instances.
Christmastide: no mention of “sin” in Latin or English collects.
Lent: 5 collects mentioning sin in Latin; the same 5 use the word “sin” in the 1974 English; one use of the word “penitent” in Latin, rendered as “repentant” in English.
Eastertide: 2 collects mentioning “sin” in Latin. English uses the word “sin” for the same two collects.
Sunday collects in the year: 3 mentions of “sin” in Latin; 2 mentions of sin in the alternate collects in English for the equivalent Sunday; 1 mention of sin in the main collect and also the alternate collect in English. One mention of sin in the alternate collect, but no mention of sin in the Latin collect for the same Sunday nor the main collect in English.
I won’t bother to go through all the collects for the saints, but you can get the picture. Neither in the Mass, nor in the collects, was there a systematic conspiracy to eliminate the word “sin” from the Mass. Fr. Z. probably is referring to the pre-Conciliar Missal vs the post-Conciliar. Still, “sin” has most certainly not been eliminated from the Mass, whether in the order of the Mass or the collects.
I’m not sure however, how comparing whether “sin” is used 7 times or 70 times is really helpful in determining which liturgy is better than the other.
All three forms of the penitential act mention sin/sinning.
Nor have I, at least not recently.