The rule was born in the Gilded Age as a deliberate class signal. Wealthy Americans wore crisp white linen on summer vacations at Newport and the Hamptons, then returned to dark, heavy city clothes after Labor Day. It wasn't about aesthetics — it was gatekeeping.
Old-money families used the rule as a social litmus test to identify (and exclude) the newly wealthy, who didn't yet know the "code." The rule trickled down through fashion magazines and etiquette columns until it became accepted as gospel.
