When people have a hair-trigger on bigotry (no pun intended lol), the smallest thing can unleash it. I don’t doubt there were some guys with man-buns who were annoying, but it seems exaggerated, yknow? In a Freudian, subconscious way:

People were uncomfortable (more or less consciously) with a man being beautiful, so when that man does something wrong which is acceptable to criticize, then all of that frustration becomes fixated on the haircut, as if the haircut precipitated the entire thing. Similar story in the workplace: woman managers are called misogynistic slurs and “bossy” because people have unchecked misogyny which vents out disproportionately on the smallest wrongs. Or a black man shoplifts, then every suburbanite gets kirked up about black people in general, resulting from the suburbanite’s alienation but channeled through their latent racism.