Why can not edit own post?

Not desiring to look stupid is yet another reason to want to be able to edit it. It’s also an incentive to not make a post. If people refrain from using their real names or posting links to personal sites, it would be hard to identify them, anyway.

I gave my opinion. Time will tell if the prohibition on editing one’s posts stifles contributions or not. You’ve now got to be extra careful about what you post and triple check any code you contribute to make sure it contains no errors because you cannot change it later.

You can always ask a moderator to make the change for you.