“A great deal of modern-day grammar confusion stems from people not understanding the role of style guides. Their rules are not meant as definitive statements on what’s right or wrong. They simply work as playbooks to be followed by anyone who wants to follow them. But the rest of us are not bound by them–a fact some people fail to understand.”

June Casagrande, The Joy of Syntax: A Simple Guide to All the Grammar You Know You Should Know

(I will add that I don’t call the contents of style guides “rules.” I call them “guidelines.” Furthermore, I usually say that unless one is paid to follow a particular set, one need not follow any at all–unless one wants to make an editor very happy. Run wild, run free!)