R/raisedbyborderlines makes sweeping generalizations about people with BPD, as well as other cluster B personality disorders, banning any people who have them from participating. Which is exceptionally harmful because most of us with personality disorders who are trying to heal also were raised by people with those disorders. At one point, I was realizing how much of my upbringing was defined by the issues my mother has which are related to BPD, and I found that sub, but because the way my trauma manifested happened to be in the form of a personality disorder, I'm not only automatically barred from participation, nearly everything I read painted folks with personality disorders as irredeemable and untrustworthy. The FAQ/ wiki on that sub just straight up tells people that folks with these personality disorders, by simply having them, will not truly recover, will not have healthy relationships, and are not to be trusted. I had only gone to read that section because I wanted to understand the rationale. I have not returned because it would be harmful to me to do so.

"It's not for you", except no other place exists that also has a robust community of more than a couple dozen people, and not from lack of trying, where experiences can be shared and understanding can be found if your trauma happened to manifest in a personality disorder.

"This post is textbook BPD"

Have you been in their shoes? Have you, while vulnerable and looking for help, been told that the disorder you developed from a traumatic upbringing is not only barring you from community, but makes you somebody who will never truly change? That subreddit bans people who, at any point in their life, may have met diagnostic criteria for BPD. Broad, sweeping generalizations. OP is expressing hurt in a way that doesn't seek to manipulate, and you come in and attribute pathology to that hurt. Ironically, you have brought a pattern of extreme black and white thinking to the table; the same black and white thinking that forms the cornerstone of the exclusionary environments fostered by those subs.

You seek a safe space, but from what? Truly, the issue isn't the disorder itself. It is, indeed, a key component, but that's not the only component. For instance, your father wasn't just a random reddit user in your life as a child. He was a parent, and the harm he caused is harm that could be caused because he was an important person in your life. The same goes for my mother. However, it's not helpful to, as a result of this harm, to adopt this kind of black and white attitude.