It's certainly not true of everyone as I have BPD and I don't have sex. I just don't want to and I don't think it's worth doing something I really don't want to do just for companionship which might be horrible and is likely to be temporary.
But it is very common in people with BPD with all genders, though it also seems to be common in life generally. Most people want to feel needed, if not loved. Most people want physical affection. Most people want to be doing the things 'everyone else' seems to be doing. And when you find someone you like, it's natural not to want the other person to end things. I doubt anyone enjoys rejection or abandonment or knowing they weren't enough for someone, but with BPD all the resulting emotions are magnified so there's an even greater desire to do whatever it takes to avoid having those feelings.
There is also a lot of pressure, direct or otherwise, to be having sex. In the media, on social media, pressure from friends/family/colleagues. People who don't have sex are seen as being weird and wrong. A lot of people are concerned by the lack of sex in someone's life, but they are much less concerned by people who are either putting themselves in dangerous situations in order to get sex, or consenting to something they really don't want because anything is better than the relationship ending. This all adds to the feeling that it is necessary to be having sex, that people who want to wait before making that commitment are doing something wrong, that we're in some way a failure if we don't have some sort of sex life. This raises the stakes even higher as it makes being alone seem even more terrible, which makes the thought of rejection and abandonment even more terrible.
Even my therapist told me I ought to be having sex. No, I shouldn't. The only way I'm going to have sex is if I consent to an unwanted sexual experience and how is that a good thing to do? It scares me to think that she (and maybe other therapists) are going around saying things like this to vulnerable people who could then put themselves into dangerous situations in order to do what their therapist suggests will make them feel better.
I'm not criticising anyone who genuinely enjoys sex with different people. There are obviously risks involved and I hope everyone is being as safe as possible in all kinds of ways, but making a conscious choice to do something you enjoy is different from feeling you have no choice but to have sex.