I think you have to consider that these conversations are taking place in public. When people reply, they're not necessarily replying to convince the person they're speaking directly to (this is often impossible), but rather to convince the reader.

I also didn't get the impression that the parent comment was being unreasonable or resentful. Lisp is often portrayed as being special and a secret weapon. It's reasonable to question that given how little it ends up being used in comparison.