If you ask me it is all just a roll of the dice. Meeting someone in general will always be that way. For all you know you could have grown up living next door to the "one" As has happened in some cases. Other times you can just randomly bump into them on the street or at bar. Being online in general is just an extension of the latter if you ask me. That said I wouldn't put all your chips into an online dating site unless you are just looking for a fling cause statistically that is what you are most likely to find.
Now that said my advice would be just get out there and let life come at you and remember you will know when you found the one for you. It doesn't matter if it is online, at a bar, on the street, at work etc, you will know and you will get together when the time is right. Just remember to keep your mind and heart open, cause you may already know that one special someone and not even realize it lol.