> There are still quite a few places that will reject a candidate out of hand for not wearing a suit. I find that troubling, just as I would find the opposite troubling.

Agreed, this is an indication of toxic culture on both sides.

HOWEVER. I would say aside from the grooming bit, the whiteboarding advice is the best possible advice for anyone. My mother can happily tell me to wear a suit, but she's not in a position to educate me about my field. A school had better fucking be, or what is the point? The technical knowledge—if they teach it at all—is itself is easier gained online than from a school.