I disagree. Especially on technical subjects, it's bad to leave incorrect information. And that's why I sometimes strike out part of a post: it makes it obvious it was wrong.
The part of my post that you quoted should also go hand in hand with this one:
Edit your original post and add that you were wrong. Mention that member X corrected you and taught you what mistakes you did. Don't be ashamed of admitting that you are wrong and that someone else knows better.
I am not suggesting leaving the wrong information there. I am also for editing it, but not deleting it and trying to covering your tracks somehow.
An example:
The topic of discussion is bitcoin's privacy and anonymity. A user asks if bitcoin is anonymous.
User A replies: Yes, bitcoin is an anonymous coin.
User B says: Bitcoin is only semi-anonymous. Your real name and private information isn't printed into the ledger and is not directly connected to the address you use, but if you connect that address to an exchange that has your real name, or other addresses which might lead back to you, it's possible to follow the money and perhaps discover your name.
User A was wrong in saying that bitcoin is anonymous. But he was partially right as well because your name, address, location, photograph, etc. isn't recorded on the blockchain. When users C and D read the thread, I think it gives them a more clearer picture to leave the reply of User A as well. They will be able to learn that bitcoin is anonymous, but not in the way that many people think it is.