At least special margin requirements have always existed, and usually day traders know to avoid them or how to deal with the special requirements with a broker

At least special margin requirements have always existed, and usually day traders know to avoid them or how to deal with the special requirements with a broker that allows you a more sophisticated view of the market. e.g. for Interactive Brokers, you look at this list and know you're going to have a pain trading these stocks: https://www1.interactivebrokers.com/en/?f=%2Fen%2Ftrading%2FViewMarginStocks.php%3Fcntry%3Dusa%26amp%3Btag https://www1.interactivebrokers.com/en/?f=%2Fen%2Ftrading%2F..... Because RH abstracts those details away to make the interface easier, the only hammer they could use was to ban trading in those securities.