Do you mean people who meet on the internet and then start relationships in real life?
If so, then I think it's fine. I have a couple of friends who are dating people they met online, one of whom is getting married, and he's a great guy...just a bit shy.
How else do people meet people these days? You have just as much of a chance of meeting a psycho (or a sponger, or a jerk) at a club as you do through the internet, and you can use the time before you meet to get to know them, screen them a bit.
Of course, you gotta be careful about how you meet them, too, but that's common sense...