This has nothing to do with understanding the scope of Mesorah.
Actually, it has everything to do with it. Not every detail – or anywhere close – of how mesorah operates, it’s boundaries, scope, it’s halachic weight against various types of other halachic factors, etc, will you find verbatim chapter and verse. But only an ignoramus takes that to mean they therefore aren’t true. You want to find out, ask one of the R”Y’s who still stand behind mesorah for this today.