This is a golden wiki rule dating back to the very early days and I am very much into it. I teach this as the very first thing to new people interested in wikis. While this may not appear very important for edits in the first place for your own posts it is indeed very much so if editing foreign posts. That's actually one thing that irritated me on bugzilla and currently irritates my on phabricator or on TUX.
Edit: One could argue that providing a summery by adding an Edit: to the post like I am doing it now is enough but in the long run Flow supporting such a feature will be nice I believe.