The statement was made about not worrying about where kids got their clothes with no dress rules and more about their insides and learning. Kids may dress horribly by the standards of some in this forum but I assure you the money spent on it matters to the kids. A $300 Supreme t-shirt and similarly priced limited edition sneakers (or lack of them) cause just as many issues as it ever did in the preppy era.
The solution used here in many schools is SMOD, standard-mode-of-dress which is non-jean pants and collared shirt for both sexes and no visible logos allowed. No logos allowed keeps most of the taunting away as most can't tell cheap from expensive without a logo to judge.