i think it was something about like, lets say somebody edited their post to just say "FIXED" and then somebody had the same problem. They would never know the answer. At least, i know that for the topic
EDIT: (straight from help section rules)
Q: Why can't I edit posts in the help section?
A: There is a severe problem where people edit their post to remove their question after their problem is resolved. This prevents future visitors who have the same problem from finding the answer.
