I didn't say it was easily treatable, just "the most treatable personality disorder."

It has a higher remission rate (meaning not meeting DSM criteria for diagnosis) through therapy than any other Axis II disorder, unless you want to count a lot of people "growing out" of AsPD in their 40s (reality is they either smarten up and just camouflage better, get locked up and people don't see the reality, or die).

Some therapists will place a limit on how many people dx'd with BPD they see, or just plain won't see someone with that diagnosis because of the stigma and propensity to countertransference.