Think of meds as something to take for symptoms, maybe. With BPD we have intense anxiety and/or depression and there are meds for that. For the causes, there is therapy.
To me, BPD is like a stunted development. We do reach adulthood, but we haven't developed fully. We have immature spots in our development that affect our perceptions which in turn affect how we deal with things like being alone, being in a relationship, speaking up for ourselves, so many things. We can feel hopelessness and anger intensely and easily and that can lead to depression and anxiety.
Anyway, as far as meds go, if they are suggested and are helping, then that's good.
If you are not sure about the role of meds in your treatment, I really encourage you to talk to those who provide your care.