It is social Piety. People that are on this or other forums are here to get an idea across, not impress others with flawless punctuation. It’s not your place to “be helpful and correct it”. Those that do it, come off as Grammatically Pius, whether it is your intent or not.
Sorry to see that you're so mortally offended by something as simple as someone's effort to help another improve their basic literacy.
I've never been offended by someone's helpful correction to my spelling or grammar, and usually thank the person for doing so.