“What carries the day is the Mesora.”
That isn’t really accurate.
“how Klal Yisroel accepted things”
There are many examples of things that were never accepted in the past that are accepted today, such as universal kollel learning. And things that were fully accepted such as the lack of a need to worry about chodesh flour (at least for Ashkenazim) are being challenged based on texts, not mesorah.
Rav Soloveitchik’s son, Prof. Haym Soloveitchik, elaborated on this in his brilliant essay, “Rupture and Reconstruction”. The Shoah broke the mesorah and we are now have a text based tradition. That generates both leniencies and stringencies, and leads to innovations that our grandparents would never have imagined.