Online dating, you meet strangers.
In person, you meet strangers.
The problem is that these people you mention get FOOLISH with online dating! I'm not really sure why they trust someone so quickly, but they do.
There's nothing any more dangerous about online dating than meeting people in any other way, as long as you keep your wits and your senses about you. Don't trust someone you've ONLY met online any more than anyone else you haven't really "met" in real life. Insist on a real-life meeting in a public place for the first time and go from there.
These people are online demonizing online dating because they are approaching it foolishly (which apparently they do in real life, too)
EDIT - comments like bluebell's are disappointing and suggest the kind of predjudice that faces online dating. "ONE" experience put her off? How many conventional meetings go just the same way?
Once again, it comes down to how smart the people are about meeting. Sure, it's easier to lie online. That's why you have to go into the first meeting without expectations and without trust. Building it from there.