I think a person CAN change using a variety of resources, one of which could be something someone says on a message board. But I don't think that the way they might end up changing is so obvious right away - it takes a lot of time and the change is for the other person, not us, so it might look different in the end from what we imagine it should be.

I don't think this means its meaningless to provide excerpts from our own lives and experience to try and help - only that saying it in love with the best of intentions and then letting it go into the other person's life to do with it what they may is probably the best course of action. It's kind of like giving a gift - we give out of care with no strings attached and the person can do with it whatever they want because now its all theirs, you know?