Welcome to the all-new iMore Forums! - We're still moving some things around, so you may see a few quirks here and there, but we're working on getting things fully completed as soon as possible. For now, take a look around, and if you run into any major issues, please let us know in this thread!
You don't want someone to be able to go back days later (possibly after significant discussion) and materially change (or possibly delete) their post. It skews the reading of the thread.
If posters have additional information to add at a later date, they should just add a post to the thread.
Once you post to a public forum, you don't "control" the post. If you want to "control what [you] post forever", then perhaps a personal blog or website is the correct avenue for that.
Editing a post long after the conversation has continued modifies the meaning of thread. If it happens to be a thread that you started, you can always ask a moderator to close the thread.
Blog comment posts get date/time stamped when posted/modified... So one could notice a time/date stamp that is significantly out of sequence...