Remember though, a certain demographic of small customers is composed of customers who are small because they are young and only just beginning to make themselves a career path. Starting from the bottom. The same small trader in 20 years could some day be a not so small trader, after numerous promotions, raises, or establishing a successful small business. Not to mention possible successful years at trading. The guy who is 63 and took a small lump sum from a pension and has $5k to trade counting most of his savings, well, his profitability as a customer probably won't increase all that much. The 24yo guy who just copped his first promotion on the job and a nice bonus along with a large income tax return and a bit of freelance work, to come up with $5k, for instance, is likely to stick with the broker who treats him like a valued customer, and when he actually IS a valued customer, maybe he won't be eager to take his money to the brokers who didn't want his business before. Just sayin. PDT rule isn't all bad IMVHO. But it does eliminate a lot of potential flexibility for brokers and traders who do see potential in small accounts. And I also think sometimes the govt and it's various agencies gets a bit carried away with protecting people from themselves.
As described, you generally just try to either get them to leave on their own by making it expensive to do the thing they're doing that costs you profits. The benefit of that approach is that if they're stubborn you're fine with them staying because you increased the revenue from them to cover the additional costs they're driving. In some lines if business though, like accounting or financial management, you just straight up fire them. I'm sorry, our firm will no longer be able to do your accounting.
PDT rule just drives potential equity traders into trading futures instead, where they blow up their accounts even faster. It's like not letting someone own a pocketknife but letting them buy a chainsaw at the store down the road. I'm surprised they haven't banned $500 intraday margins for ES yet.
Completely anecdotal, but I'm guessing far more people just give up rather than trade ES. Even the comments here point in that direction, the vast majority of folks just aren't comfortable with the concept of futures themselves, with the minimum size an extra deterrent.