No one should ever buy a Kevin Hogan book, or any Kevin Hogan product, nor attend any of the Kevin Hogan scamfests and rip-off seminars. The guy is a 5th rate huckster.

Never said Cialdini said anything new, Cialdini has organized the main principles of Influence, in a way that are easy to understand. His book is worth reading.

Virtually everything sold in "direct marketing" these days is complete utter rubbish, meant to try and sell the books.
But modern Influence has changed a lot since the 1950's.
Cialdini does not cover many of the most recent techniques.