Few answers get any sort of editing or updating over time. If you’re worried about deleting information the obvious solution is to automatically hide the text

Few answers get any sort of editing or updating over time. If you’re worried about deleting information the obvious solution is to automatically hide the text when the poster says it’s outdated. At which point there’s little wrong with letting someone flag all their posts as likely outdated upon leaving. But this is where the business of SO comes into conflict with providing useful information on SO.