The difference is, VDH has such a calm and rational demeanor, he appeals to independents who would never pay attention to people like Hannity or Ingraham. Steyn is another, but a bit of an acquired taste. VDH gives the impression he is genuine and objective which is key because undecided people are only going to be persuaded by logic and rationality, not by bomb-throwing or hyperpartisanship (or hyperTrumpism).
I absolutely agree and you stated his appeal succinctly and accurately.