The two main passages on das Man (the “they”) in the first division of Being and Time (sections 27 and 34-38) present us with a jarring shift in tone. Though Heidegger repeatedly emphasizes that he’s not making any kind of evaluative judgment, it’s hard not to walk away from those passages believing that living in the “they” really, really sucks. A couple of my students emphasized that Heidegger does say that Being-with is an irreducible aspect of Dasein’s Being and even wanted to put a positive spin on it — for instance, isn’t it kind of cool that we can use “idle talk” as a way of expressing our simple desire to hang out with each other? Yet if Heidegger wanted to emphasize the good side of the “they,” he would have had to write these sections very differently.
One could chalk this up to Heidegger’s personal conservatism and distrust of bourgeois mass culture, etc., but I think there may be a reason internal to his project. He says over and over that his goal is not to carry out anything like a philosophical anthropology, but to cut straight to the question of the meaning of Being as such. His path requires him to start in everydayness, and everydayness does give him a lot of interesting and useful ontological clues (which he shows in the awkwardly placed sections in chapter 6 on reality and truth) — so that one might think look at that evidence along with his critiques of scientific reductionism and conclude that he was simply favoring everyday know-how over fancy book-learning. And so he has to highlight the aspects of everydayness that militate against any authentic disclosure of truth and enforce a kind of unreflective utilitarianism coupled with conformism for its own sake.