I didn't go into much depth on my position on BPD because it was outside of the scope of my reply.

I think there's a trend in mental health for professionals to diagnose people with BPD on the first visit or first admission to hospital without taking the time to assess the history and current circumstances of the patient. There's also a lack of recognition of the impacts of trauma, especially if it's fresh or it's a person who has experienced significant institutional trauma. Another aspect is that BPD is often used where a clinician is disinclined to investigate dual diagnosis or comorbidities, or even just complex circumstances. With regards to this, it's sorta tangential but I worked in an organisation that would conduct the MMPI on candidates. One candidate had just gone through a very recent and messy breakup just before taking the MMPI and the results that came back from this, as interpreted by the expert in the MMPI that we would consult, indicated that this candidate was a huge walking red flag. Without going into depth on it, this wasn't actually the case and it was just reflective the emotional state of the person at that particular moment in time. Of course this isn't the exact same thing but when someone presents at an emergency department in a mental health crisis, it takes a very skilful head psych to recognise the difference between diagnosing an emotional state and diagnosing the patient in a holistic sense.

BPD often gets used as a "too hard basket" or Mental Illness-Not Otherwise Specified diagnosis. There's a major gender divide in diagnosis too, where afabs get BPD diagnoses and amabs get PTSD diagnoses, even when presenting with similar symptoms.

Last of all it's really common for late-diagnosed autistic people and ADHDers to get misdiagnosed with a mood disorder prior to getting an accurate diagnosis, and BPD is one that comes up often here. There was a recent study has found that, of a range of medications, one of the most effective (and only effective ones) for BPD is methylphenidate, aka Ritalin. Of course, the overwhelming majority of the people in the study were women due to the gender disparity of BPD diagnosis. Without delving into the nitty gritty of the study design, my immediate question is - how many of those subjects are women who are actually ADHDers who have been misdiagnosed with BPD? Because there's another cohort of people that respond in a similar way to methylphenidate and there's a lot of overlap between this demographic and the one that the study targeted.

Like I said in above, I have encountered people who are genuinely BPD. I'm not saying that it doesn't exist or that it shouldn't be taken seriously, far from it, and I'm not going to try and convince anyone that my opinion holds more water than a mental health professional, it's just that in my opinion the diagnosis of BPD needs to be viewed with healthy skepticism - is the person who is trying to convince me that I have BPD an abusive partner who is not a professional in a clinical setting, as OP described? Does the person have a history of recent trauma or significant childhood trauma? Is this a first-port-of-call diagnosis or one which is being made in an urgent care setting? Has substance use disorder been considered as the cause of the symptoms that the patient is presenting with? Have other conditions, especially autism and ADHD, been overlooked? It's in these sorts of situations where I think that healthy skepticism of BPD diagnosis is crucial.

That's not to say that all BPD diagnoses are incorrect under those circumstances, at least aside from the abusive partner example, but it needs to be weighed against considerations like those ones.

With all that said I'm wondering if I'm using the term skepticism to refer to like a rigorous, scientific approach to assessing how the symptoms and their etiology stack up against the diagnostic criteria but it's giving the implication of skepticism in the sense of something like "climate change skeptic" or "COVID skeptic", which is just a sort of reflexive rejection of facts and essentially the opposite of what I'm trying to imply with that wording choice.