I already created a thread to request that. Come add your voice to it.
Yes, for longer than 5 minutes. Unlike vbulletin board, where only moderators can see edit history, Discourse allows all posters to see a post’s history. So what harm is there in allowing a poster to edit their post? They can’t “re-write the past”. What they CAN do is fix an awkward typo or add a clarification that they realize they need after a reply or two.