What it might mean, in my somewhat cynical opinion, is that psychiatrists often don't know what they're talking about, and that the so-called diagnoses they label people with are not reliable or valid.
We should remember that BPD has never been reliably identified by any brain, genetic, or physical marker - despite decades of failed efforts to identify these markers. "Diagnosing" BPD always relies upon subjective judgments made by the therapist, judgments which can be mistaken and will never be 100% agreed upon by different psychiatrists.While the symptoms called borderline are real in innumerable variations, it is far from established that these symptoms/traits go together in any reliable way to form a common illness, whether that supposed illness is called a borderline personality disorder or borderline traits.
There are many problematic questions surrounding the BDP label.
For example, someone could have 3 borderline symptoms one week, and 5 the next, but then 4 the week after that. So then they would be non-borderline in week 1, borderline in week 2, and non-borderline in week 3. Does this person really have a borderline illness only in week 2?
Or, does it make sense that person A could have symptoms 1 through 5 in the DSM list of BPD symptoms, and person B could have symptoms 5-9 only, but both would have the same borderline illness, despite having only one symptoms in common but four totally different symptoms?
Is it logical that each of the 128+ forms of BPD that supposedly exist (from combining the 5 out of 9 symptoms in every possible way) actually constitute a common syndrome (i.e. cluster of symptoms that reliably occur together) or "disorder"?
Can psychiatrists reliably "carve nature at the joints" to determine when someone has (or does not have) a borderline disorder, has (or does not have) borderline traits, or is "normal"?
Can a psychiatrist reliably determine when the degree of a person's emptiness, or stormy relationships, or black and white thinking, is intense enough to warrant classification as a "borderline" symptom or trait? Where do we draw that threshold? And if it cannot be drawn reliably, is BPD reliable? Etc. etc.
Perhaps you can ask your psychiatrist these questions

If you do get good answers from them, please do share on here.