I don't think climbing the ledges anyway despite the clear warning is going to cause people to disappear... especially since there are some people who've tried it and are still around now, right?

But... it might be the same force preventing ledge-climbing that also causes the occasional disappearances, you've got a point there. Sort of makes you wonder if it's a controlled thing, or if even whatever's playing around with us right now doesn't fully know what they're doing.