Online, discussions of grammar tend to display confusion about what the subject is, and the usual admixture of rubbish and emotion does not help.
There is, of course, the confusion between grammar as grammarians and linguists discuss it technically, and spelling and punctuation. But other, unstated meanings are often involved.
A post by Lucy Ferriss at Lingua Franca, “Grammar: The Movie,” identifies some of the additional meanings that surface in a new documentary.
Spelling errors: If you write it’s for its in your cover letter or resume, or confuse there/their/they’re, you’re probably not going to get the job. But these are merely spelling errors, as likely the result of carelessness as ignorance. Of course, they’re obvious, so easy to spot that even a manager can see them, but they are still trivial.
Bad writing: Lord knows there is plenty of slack, inexpert, and impenetrable writing to be found, but that is not a problem for grammarians to address. Academic writing, for example, is notoriously wordy and opaque, but it is usually grammatical.