If common lisp were obscure and not something that was very common knowledge you would have a point. I had never heard of this ability that he brought out in the open, because of having this posted on HN I now learned something new today, something I can take with me and teach others or use in my daily job.

That in and of itself is fantastic and exactly why I like posts such as the one he made.

Let me make sure I'm understanding you correctly: You're saying that the Linux kernel's ability to easily run arbitrary code when a core dump occurs is fundamental knowledge that all reasonably experienced C programmers (and most HN readers) possess?