Allowing permanent post editing in the Community Showcase section would allow users to update their posts with new screenshots and information (compared to constantly making new replies for nee screenshots). It’d make showcase updates “cleaner”.
The problem you have there is edits to the original post won’t bump the thread, so nobody is going to know about any updates unless the OP or someone else posts a reply to inform people. Which would then also require you to scroll back to the top of the post to see the edits.
Alright, here’s another case:
My dating sim Love Like a Tower has a dead download link. I can’t change it in the op, so anyone looking to play would have to scroll to the bottom of a 44 message thread for the new link.
Also it would bump a terribly dated thread.
This is now fixed, unfortunately I can only make it site wide.