107. It is to be observed, also, that they have strayed from the path of truth and right reason who, led away by false opinions, make so much of these accidentals as to presume to assert that without them the Mass cannot fulfill its appointed end.
More likely, people would assert that a fully participating assembly is a more perfect expression of the heavenly liturgy, and a more effective means of communicating God’s grace.
108. Many of the faithful are unable to use the Roman missal even though it is written in the vernacular; nor are all capable of understanding correctly the liturgical rites and formulas. So varied and diverse are men’s talents and characters that it is impossible for all to be moved and attracted to the same extent by community prayers, hymns and liturgical services. Moreover, the needs and inclinations of all are not the same, nor are they always constant in the same individual. Who, then, would say, on account of such a prejudice, that all these Christians cannot participate in the Mass nor share its fruits? On the contrary, they can adopt some other method which proves easier for certain people; for instance, they can lovingly meditate on the mysteries of Jesus Christ or perform other exercises of piety or recite prayers which, though they differ from the sacred rites, are still essentially in harmony with them.
And these other expressions of love and meditation will take place without explicit permission of the hierarchy or local clergy, and hopefully without interference from one’s peers.
Only God knows if a person is truly baffled by the liturgy, or moved to a different direction, or obstinate in refusing to engage in the role accorded to the laity. I do know that the practice of clergy sitting in the pews and assuming the role of a congregant is deeply frowned upon. In light of MD 108, I wouldn’t know why.