So, your parenting method then, if I'm understanding correctly, is to not try to protect from injury? Then why bother with the fireplace?
Our "parenting method" is based around teaching our daughter right from wrong and to listen to what we say. We chose not to prevent her from getting to things (locking cabinets, removing photos and items from low bookshelves etc) we didn't want her to by teaching her to not touch the, or get in them. The main reason we wanted to do this was because we felt it was more important for her to learn where she could and couldn't go rather than preventing her from going into them. This has served us particularly well when we go to other peoples houses.
We padded the fireplace and put safety plugs into the sockets for almost the exact opposite reason, to protect the children of the kids our friends bring over (6 months+). I didn't even want to do the safety plugs, but my wife wanted to so I agreed.
You see, if I am cooking on the bbq pit outside, I know my daughter can get hurt. So, we teach her where she can go and what she can touch. If I thought it was "baby-proofed" and she was "prevented" from touching it, I wouldn't pay as much attention (aka - the safety plugs for wall sockets). When there is a preventative measure there, it means most people pay less attention. Thats not a bad thing, just human nature and why we put those measures in place....because it's easier than the alternative.
My daughter is three and almost ready for the training wheels to come off her bike, BUT she rides with a helmet. See, we believe in doing things to help keep her safe, but not preventing injury and I think there is a difference.
As earlier stories in this thread describe, once some kids get to a point where they are going to do what they're going to do, little can be done. Because we never got to that point, we would never use a "leash".
If your 2 yr old was a flight risk you would teach him a lesson by letting him get lost?
Of course I would never try and teach my child a lesson by putting them in harms way, BUT to use an analogy when my daughter was about 10 months old she wouldn't stop walking towards the side of the pool. She had to physically be stopped or she would walk in, so one time we let her walk in. She is three now and hasn't done it since. We have put her in swim lessons for the last two summers and she is comfortable in the water, but knows she needs her floaties. And we will even let her go into the pool by herself (at three years old) as long as one of us are at the poolside and keeps an eye on her.
Again though, all kids are different.