I dont disagree in that aspect.
I think there are plenty of examples - but "speaking well" isnt the same as "saying what you mean and meaning what you say" ( so to speak )
You can win a debate against lesser abled speakers on a topic in front of a panel of 3. But if the core information you are speaking about is going in direct contrast to what everyone can see/knows, it doesnt matter how well you speak, as it quickly becomes apparent that you are either conning us or you have no idea what you're talking about.
I will add...children are quite adept at seeing right thru the BS- dont know how, dont know why- maybe from the years of learning how to manipulate in the early years, but they have an uncanny ability to sense "BS" ;)