The goal of these content guidelines is to help us to:
These content guidelines aren't about "correct" and "incorrect" writing. They are about effective writing for our target users. Of course, effectiveness involves correctness to some degree, but only correctness as judged by the audience, not as judged by an appeal to authority.
The examples included in these guidelines are for comparison's sake, not for exactness.
These guidelines are a living reference, and we welcome changes. The most effective arguments for changes are those based on effectiveness, not correctness.
For further reading, see linguistic prescription on Wikipedia.