There's a ton of social aspects and impacts that have to be considered and tested, and I think you've only scratched the surface. An edit function would add a s

There's a ton of social aspects and impacts that have to be considered and tested, and I think you've only scratched the surface. An edit function would add a substantial amount of new UI/UX and interface elements. There are still Twitter features (Spaces, bookmarks, many of Twitter Blue's additions) that have been on the smartphone app for year(s) that are still inconsistent or half-baked on the web app (and sometimes vice versa). And there would have to be substantial additions/reworking to the API. On a more technical issue, no doubt much of Twitter's architecture (e.g. caching) has been built with the assumption that a tweet's content is immutable. I imagine that breaking that assumption impacts a lot of underlying systems.