There are many situations where the ability to edit a post a "long" time after it was originally made is useful. Three come to mind right away:

- Because of new information. One could always make a new post, but that fragments things. If one adds enough context to avoid fragmentation, the thread may become unnecessarily long. Better to just edit what was affected.

- To correct errors pointed out in later, often much later, posts.

- To keep threads such as Do programs, participant lists, flight/hotel plans, etc., up to date as plans develop and people sign up or cancel. Editing a master participant list is much more effective than creating a new one each time.

While editing can be abused, I don't think the benefits of a time limit outweigh the downside.