. . rabble rousers would be out of business.
The listeners have the power to vote. By skillfully playing to his audience the rabble rouser has power over them, and directs their vote. He has this power over them because they have given it to him - in return for freedom from having to think for themselves. They become his surrogates.
Humans are semi-pack animals and a majority of them are looking for a leader to follow - rather few are leaders, perhaps a few more are independents. If this were not so Hitler would have remained a paper hanger.