If it reliably lead to the truth, it would be called epistemology, not rhetoric.
Since the majority are incurably vulnerable to rhetoric, what they need is a personal rhetoritician, the way they have a personal doctor. If they change any non-ornamental beliefs, their rhetoritician vets the change. (If I'm not mistaken, this person used to be called 'pastor.')
However, it's also undeniable that a few do not need personal rhetoriticians. (The pastor, for example.) This is clearly the high-status behaviour. And the person most likely to say, "Buh! I don't need one either!" is exactly the person who needs one most.
In short the peasants are fucked. They can be oppressed for their own good, or they can be oppressed for fun and profit. They can be forced to have a rhetoritician, or they can function as snacks for any passing rhetoritician. There is no 'not oppressed' pathway on the table, which is why we call them peasants.