Hmm. On one hand it preserves lulz.
On the other hand it's annoying if you want to do something perfectly logical. Like you realized you fucked up a link or something and you want to fix it. It'll also create extra work for mods to edit the OP of good stickied threads where there are collections of resources (best software) or sales etc, when the original poster can't do it.
I'll see what people think in this thread, but I'm siding on no because it creates more work and I think people edit posts for legit reasons more than crazy people edit out stupid/funny.