The issue of birth control is a good example of why the laity should have limited influence in the Church.  The laity, having only common sense to work with, were not able to understand that even though ABC and NBC both prevented reproduction, one was sinful and one was not.  Clearly, the laity lacked the competence to exercise moral judgements on their own.
Pope PaulVI, on the other hand, not burdened by common sense, was able to see the moral difference between ABC and NBC, and was able to present that difference to the laity with such insight and clarity that the use of ABC is long in the past.