For a long time I thought that the comment that I left in 2011 after the PHP bug was sufficient. Remembering it today I edited the answer at the same time that I posted here.
Now I could be faulted for not having responded to the comments in 2015. However I was taking an extended break from stack overflow after getting annoyed at the moderation of https://stackoverflow.com/questions/11314077/algorithm-for-e.... When I came back, dealing with the variety of things that could have further annoyed me while I was gone did not seem worthwhile, so I didn't. (It remains a pet peeve that a lot of moderators remain quick to close algorithm questions because they do not recognize DP-type problems as things which are more likely to be answerable by people with a CS background than a math one.)
It is amazing the number of replies in this entire HN thread that have no idea every single question and answer on Stack Overflow is editable, even by an anonymous user. The first item in my list was Stack = wiki for a reason!
As a cautionary example, see https://stackoverflow.com/questions/5021456/how-does-mongodb.... The question was why MongoDB was by default able to avoid the equivalent of SQL injection attacks. My answer took what was in their FAQ at the time, and expanded upon it based on advice from D.J. Bernstein - who is famous for his ability to write secure by default code.
Then it was discovered that PHP volunteered to create security holes in MongoDB. Then it was discovered that multiple other languages and libraries likewise volunteered to do so. Had they followed the good advice that I was quoting, the problem wouldn't have happened. Despite the other faults of MongoDB itself, in this case it was truly innocent. The security problem wasn't in it, but in the libraries that were written around it. It made it easy to write secure code and they didn't.
But the result? From the point of view of a naive programmer, not long after my answer appeared it was revealed as misleading for PHP programmers. A few years later, it was actively misleading for other languages. And while the advice remained technically correct - which is why I left it - it has been criticized on reasonable grounds by several other people since.