There's absolutely no verifiable truth to that absurd claim and it demonstrates the problem with online communities: they're often populated by those who, like those they claim to be criticizing (narcs or otherwise), want to control a narrative, irrespective of truth or objectivity. Any cursory search in a legitimate library, academic journal or similar, would easily dispel that and prove, quite literally, the exact opposite (which I'm sure you realize). It also makes no logical sense if you even understand narcissism, and that position de facto excludes all the other types, such as covert or communal, thereby disrespecting and erasing victims across the board. Regardless, garbage is all over the internet, as are people who don't know what they're talking about. And the confusion caused by them makes issues worse, which is why I only post on here, and only occasionally. Discord is no better than reddit and arguably somewhat worse, and most of the communities are crossed over and on both, so you're being fed by the same cretinism--the only difference is that you have a different username and login for one versus the other. For your own mental health and development, I'd leave them all. If all they do is propagate lies and talk bullshit, then what's the point? What value is it adding? Nevermind the fact that there are countless groups spread across the internet that are explicitly intended to mislead people for their own purposes, and want people to be confused or harmed. Guard yourself and your brain best you can and raise your standard of engagement.

I'd also really avoid self-diagnosing, unless you've been diagnosed by a professional as having borderline, don't form ideas in your head about what you may or may not suffer from without knowing it for certain. That's as dangerous as anything else. Just focus on being well-rounded and healthy and when possible, talk to a professional about your concerns otherwise.