I think that's a good question. It appears to be one of those nanny state regulations designed to protect people from their own judgement. However, the same nanny state would have no issue with me going to my nearest casino and blowing $25k in one night on poker or the state lottery which has far worse odds than playing the stock market. I'm not arguing that it shouldn't exist, but don't understand how state-sponsored gambling is exempt from any kind of limitations. I'd modify the rule to consider only losing trades...maybe something like no more than 3 losing trades in a 3 day period.
I can argue it should not exist. It does not with futures that are more levered. If I were making the regulations, I would still have one but focus on the leverage. I would allow all DT in a margin account to recycle BP, but accounts under$25K should have 1X, not 2X or 4X. I also think 4X for an account of $25K is too high. To get 4X, the account should be >$50K. Just my opinion.
your advice sounds like the quip from Will Rodgers:" buy only stocks if they go up. if they don't go up don't buy them."
Well, you know it's not bad advice. If you can follow that advice to the T then you will make it at trading .
TDA does not provide a "warning" per se, they put a little icon next to the account number that says "PDT" and when you're restricted based on margin they put what appears to be an "EM" instead of "PDT". Once you violate the 4 open and closes you are further restricted to closing trades only. And it the 5 BUSINESS days. I got caught in this during the week of July 4 when the market was only open 4 days from Fri to Fri.