There's a difference between meeting someone on a dating site or getting to know someone over a few months and sliding into your dms, being nice to you once and then suddenly asking you to meet them in person alone.
Granted, the point is that she doesn't have these tactics or abilities because she's emotionally unstable, depressed and is unfamiliar with people. It's easy for her to be abused and manipulated because she doesn't have interpersonal skills to notice a dangerous situation when one appears.
But, yeah don't just met random people you know online IRL suddenly without getting to know them for a few months or so. I never claimed everyone online is a serial killer/rapist/predator, but there are ones out there and you never know so its best to meet with in person with a few friends and associates, people you know, and be prepared in case an incident occurs. It's just a case of forethought, which we know the main character is lacking because of her background and personality.
@criver