I think this is a case where it is essential that we be able to keep two things in mind at the same time--tough, I know, but sometimes it's just that complicated.

(1) Whether or not someone has a mental health issue: something that substantially impairs their own or others' lives.

(2) Why they have that issue and whether it's somehow intrinsic or a typical (if, at this point, unwanted) reaction to conditions they've experienced.

Psychiatrists need to keep this in mind because it's very likely that there are important differences in how a mental health issue presents based on how it arose. For instance, as you suggest in the case of BPD, it may be helpful to directly tackle the trauma angle in addition to trying to address any current symptoms.

But if we want to extend additional sympathy to people who have suffered horrors, while still trying to help mend people who have suffered them, the rest of us need to hold both things in mind too.

If someone comes into an ER suffering from a ruptured intestine, if the rupture was due to scar tissue from being shot the previous year, we still diagnose a "ruptured intestine". A lot of what needs to happen will be the same. Some might be different. Diagnosing the problem shouldn't mean that we are any less concerned about reducing gun violence--to the contrary, if anything it should make us more concerned.

There is no reason in principle that it should be any different with mental health.

In practice, we're rather better at coming up with well-delineated diagnoses of physical ailments than of psychological ones. (To the point where if something is confusing but physical, it tends to get reclassified as psychological so no-one who isn't used to it has to admit defeat.) But it still points in the direction that we should work.