It is complicated.

On one side companies sometimes have policies on the appearance of their client-facing people due to wanting to project the kind of image some customers expects (humans in general are pretty superficial in passing judgement, even when they’re supposed to be hardnosed professionals, so some client representatives will have their judgment - which in the ideal world would be entirelly done on professional grounds - affected by the appearance of the front of the house personnel) rather than because people inside that company actually care about it.

On the other side, this stuff is widelly abused in the highly hierarchical structure which is the typical company to very visibly demonstrate the power of management through making the most visibly free-thinking employees comply (or leave, they don’t care: the purpose is for it to be seen by the rest so as to induce them to “do as they’re told” and even create an environment of peer pressure for compliance, the kind of environment were you have things like for example “a culture of unpaid long-hours”).