Horkheimer saw masses as cattle ready to follow any leader

Evidence

The meaning of this slogan is simply that the people are all nothing but herds of cattle, whose nature is to follow any leader; or, to put it in a more modern way, who can be made to do anything one wants as a result of officials’ familiarity with psychological methods … Who can hold the Germans responsible for the Nazis? We know perfectly well that they would have gone over to Stalin or General Motors with exactly the same enthusiasm! — Rolf Wiggershaus, The Frankfurt School, 1631