I think you might be confusing a few things?

It’s not that it’s done for no attention whatsoever, it’s that the phrase “they’re just doing this for attention” is a way that people dismiss each other, and ironically, over-fixate on people who just want to pay for their groceries and leave, you know?

By being fashionable in socially unapproved ways, people will assume you’re being vain as a euphemism for their relative disgust, and vanity loses you a lot of social capital—aura, basically. They’ll rather think of you as prissy than serious.

But you can comment on a person’s hair if you like it, same as you would a band t-shirt for a group you both like.