My biggest problem with the whole "oh, be different, be unique, there's nothing wrong with standing out from the crowd" is that, if you do just that, you're ostracised, shunned, and taunted. While I personally think I'm a "unique" person (I mean, I saw Joker in 2019 in a trench coat and combat boots - I did receive some funny looks) I'm not the only one. All of us on here are probably seen as outcasts or weirdos, hence why we're here in the first place.
But what you also have to realise is that
everyone is unique - not one person is the same as another. When everyone is unique, no one is, because everyone is unique thus being unique means you aren't unique. It's somewhat paradoxical.
I guess like
@Mathiverse said, "be unique" = be good-looking. Nobody likes a pimply, greasy, socially awkward outcast; everyone loves a shy, good-looking outcast. I mean, there's a whole genre of them in fiction, like Archie from that shitty show called Riverdale or whatever. It's a caricature in fiction. Those brooding, mysterious guys are the types women throw themselves after and say "I can fix him!" to their friends.
Anyway, I feel like I've strayed from the topic at hand. I'm tired, bored, and lonely, so I'm in a rambling sort of mood but there's my take on the whole "be unique!" thing.