I've read Hoffer's book. One aspect of it the article neglects is that all the movements studied were cults of an individual personality: Martin Luther, Napoleon, Stalin, Hitler, Mao, a few others. This perspective does not fit the Soviet Union entirely well -- I forget how Hoffer addresses that objection.

The book is not long, and a lively read, highly recommended. Sample: Hoffer quotes a low-level "true believer" as exclaiming "We Nazis are the happiest people in the world!"