It's as Annie said- you have to use your best judgement in determining if it is safe. And always meet in a public place. The very first person I ever met from online (the old Prodigy Deaf boards...) was over 20 years ago (!); I took a friend of mine who I already knew and met my online friend at Shoney's lol. It was fine. Over the years I've met quite a few since then. I lost contact with the first person (wish I knew what happened to them, HOH...) but many if not all of the others I've met I have known them for between 9 to 17 years (some from AOL lol). One has been a better friend to me than a so-called friend or two that I met in college over 30 years ago.
It is true there are bad experiences as noted above but for the most part if you follow the advice- meet in public places (same is true for newspaper personal ads lol), if you can take another friend, tell others where you are going, if you feel uncomfortable cut the meeting short (and if it escalates- block 'em online), there won't be too much of a problem.
So far I haven't met a 300 lb bearded guy living in a basement and wielding an ax- at least not in person- yet.
hahaha