My greatest lesson has come from having the opportunity to meet the real people behind the profile...and find that they are wonderful people...some of whom are not here any more...Allie and Roger being big hearts from the past. People that I may disagree with on the boards are absolute darlings in real life (on the whole).
I agree that the whole point of discussion boards is sometimes to confirm what you think yourself...or it's to understand the other persons viewpoint, or it's to adapt your own through greater undertsanding.