Pardon the pun

Whenever I read an article or a blog post, etc. I find it amusing that people still find the need to excuse their puns. Why?

Do writers do it to highlight the pun so they can show everyone how clever they are for writing it?

Don't get me wrong, I love puns, they're like an easter egg in the form of words.

But I don't get why people have to pardon it. Is it some kind of writing etiquette that I'm not aware of? (If it is then that seems a bit ridicuous to me).