Last time they revamped the Message Board software a couple of years ago (in order to add pop-up links to silly Ancestry Surname/Locality
Books by keyword, and to add advertising space), the beta testers requested an editing feature, at least in the form of allowing a 'preview' before posting. The 'preview' button never was made functional.
The problem with 'editing' posts after they are posted is that there may be responses to an item stated. If the original poster deletes that, the follow-up post(s) may become unintelligible.
If the original poster changes their mind about something or wants to make a change or correction, for any reason, it can be done by an additional post in the thread.