Chess itself is a collection of very arbitrary rules.
They happen to be rules that people decided are fun, or interesting, or something. If the dress code isn't fun they should change it.
And for that matter... this tournament is a blitz game, itself a change of rules. Perhaps it would be well suited to a change in dress code. Formal clothes for classic chess. Show up in your PJs for a game that takes as long as brushing your teeth.
They happen to be rules that people decided are fun, or interesting, or something. If the dress code isn't fun they should change it.
And for that matter... this tournament is a blitz game, itself a change of rules. Perhaps it would be well suited to a change in dress code. Formal clothes for classic chess. Show up in your PJs for a game that takes as long as brushing your teeth.