In this manga, there seems to be a distinction between the mental illnesses and traumas villain leaders have vs. the ones henchmen have. Henchmen have things like “suicidal depression” or “alcohol addiction” or “obsessively murders everyone they love.” Leaders are more “megalomania” or “can’t stand being touched.” It’s not about culpability, exactly—some of the henchmen seem fully in control of their actions—but the leaders seem like they would have more of an ability to fit into “normal” society if they chose to.
Shigaraki talks to his father’s severed hand, so he’s definitely the most out-there of the villain leaders. He’s also the one who cares the most about whether his followers live or die. I think there’s something going on with the degree to which leaders can understand and relate to their followers.