This is a defitional retreat. The Frankfurt School were Marxists trying understand the psychology of the masses who went along with the "wars if the elites." The turned to, and incorporated, the insights of Freud. See the work of Philip Reiff for more on this. Marcuse, also a Marxist, recognized that would never be able to recruit the masses in the U.S. (because capitalism [of a flavor] was actually working to lift the lower classes out of poverty -- so he turned to "the ghetto" and the marginalized. The Critical Theorists, also avowed Marxists, took up this Marcusian focus. That's only a small part of the story, but one can draw a straight line from Marx to the -- I say again -- cultural Marxism (Gramsci) of today. See the work of Eric Voegelin and Augusto del Noce, or of James Lindsay, for more.