In an edit of another person's post, you need to change at least six characters. What if the OP just got one important word wrong (it's "atronach", not "astronach"), which means the question might not show up on a search?
I left a comment, but I believe it might be quicker if I could just fix the mistake.
EDIT To clarify: I know that I can suggest an edit, but I cannot submit one unless I change at least six characters. Should I add additional, unnecessary changes to get over the limit, or should I type "yay, edited by me", or can we just drop the limit on the number of characters in an edit?