So to recap:
Horkheimer warned in Eclipse of Reason that formalized subjective reason that optimizes means was going to eclipse “objective reason” about social harmony, the good life, the “ends” that really matter. Technical efficacy which is capitalism which is AI would expose how objective reason is based in mythology and so society would be senseless and miserable forever.
There was at one point a critical reaction against formal, technical reason that was called the Science Wars in the 90’s, but though it continues to have intellectual successors it is for the most part self-defeating and powerless. Technical reasoning is powerful because it is true, not true because it is powerful.
It remains an open question whether it’s possible to have a society that steers itself according to something like objective reason. One could argue that Habermas’s project of establishing communicative action as a grounds for legitimate pluralistic democracy was an attempt to show the possibility of objective reason after all. This is, for some reason, an unpopular view in the United States, where democracy is often seen as a way of mediating agonistic interests rather than finding common ones.
But Horkheimer’s Frankfurt School is just one particularly depressing and insightful view. Maybe there is some other way to go. For example, one could decide that society has always been disappointing, and that determining ones true “ends” is an individual, rather than collective, endeavor. Existentialism is one such body of work that posits a substantive moral theory (or at least works at one) that is distrustful of political as opposed to individual solutions.