As it was a casual remark in passing, I don't plan to debate, and "reasonably arguable" is a fairly low bar. But, Hitler had a mesmerizing speaking presence, at least for the people he connected with. He probably would never have amounted to anything except somebody in the German establishment, wanting to quell the chaos that followed the end of WWI, hired him to lecture groups of soldiers to reign them in, and he "discovered he had a voice". Once he became chancellor, it took 3-4 years to go from fairly chaotic thuggery against jews and, over time, whoever would not return the Hitler salute, to even get to Kristalnacht, and in that time he perfected the art of haranguing all Germans at one time. If you didn't have your radio tuned in to his speeches, your neighbour might report your unpatriotic behaviour.

Oh, I wasn't disputing, just asking for more information.

As a medium, I think it's one factor in many in laying the ground for people getting more and more into separate and hostile mental universes, such that a high percentage of people can believe that Obama is a Muslim and a Marxist (at the same time), and that global warming is a hoax which is part of an international conspiracy to turn the world into one socialist state. It used to be rare to find someone who thought the moon landings were faked, but now I think certainly 15-30% of Americans have delusions of that magnitude.

Oh, I see. I latched on to the wrong part of your summary

...well, I can see your point, certainly. I'm not sure if you're factoring in the increased ease of encountering opposing viewpoints, but I suspect you are :/