HN does not have an edited tag and doesn't allow editing past a brief window (for both headlines and comments). Ones that are edited are invisibly edited: there's no notification that they have been, unless someone points it out. You are wrong and your idea is so awful that I struggle to think of an idea that could be more destructive to discussion quality, especially on a site that already has a low standard of discussion like twitter.

I edited this comment multiple times. No edit tag.