PDT is problematic in modern era because it reduces the number of parallel strategies you can run on sub-accounts when you're not yet well capitalized, since each sub-account will require $25k, or at least this was the case last I checked on IB two years back. (Yeah, there are ways of running a lot of strategies on the same account, but not all platforms support this and a simple hand-constructed solution is likely to be unsatisfying.)
Adding a constraint like this on equities alone and then leave everything open is also like WTF. Why shouldn't amateurs be day trading the easiest asset out there (long bias)? The primary cause of catastrophic failure is leverage; overtrading without leverage very slowly drains you account (all in bets on penny stocks aside, but those are going to bury you on longer holding periods too).