“It is the reason we Pasken like the Shulchan Aruch and even like Bavli.”
Any yeshiva bochur can give you lots of examples where we DON’T pasken like the Shulchan Aruch and where we go against even unopposed Bavlis.
“Those with a strong, unwritten, mesorah, discredited them immediately”
Those who had no sources had to revert to screaming “mesorah” even when there isn’t one.