Are you talking about in threads that turn into a heated debate/argument, where one person changes his post a little to protect himself/herself from unwanted flack over something they posted in error?
Lol I think I know what you mean in general about this going on, but I don't see instances where people are accusing the other on THIS site. So please, give more examples. Otherwise, I personally don't see a problem with editing.
Unless you mean editing a previous post and that being meant to stand as a new one... that could be confusing, having to reread old posts even more to check for changes. But again, I don't see that. Enlighten us