So you might summarise Chomsky's book as "some people are more persuasive than others"

Does he also say that these people may be powerful because they are persuasive?

I think it's more along the lines of they are persuasive because they are powerful. The golden rule: he who has the gold makes the rules.

Well of course they're persuasive because they are more powerful. That's the main theme (as I understand it) and agree.

I was suggesting the other way is true too.

It is easy to be persuasive when you are asking people to simply remain as they are: uninformed on important matters.