Personally, if Klal Yisroel can be Meikel like the Bach for Chodosh (which is M’dioraysa), they certainly can be Somech on the Rama, Tos. & Rashi for Zimrah.
Oh, is that the way halachah works? Take the “weakest link” and apply it across the board?
Maybe aderaba, we should copy what we do for ba’al yeiraeh of chametz, which, since we do bittul anyhow, is d’rabbonon, yet Klal Yisroel is quite machmir.
You can’t compare the various inyonim. Each series of halochos has its own history and dynamic of how the hanhagah developed.