Most books aren’t rejected because the stories are “bad.” They’re rejected because they’re not “ready to read.” In short, minor stuff like typos, grammar, spelling, etc.
I don’t mean places where we, as authors, deliberately break the rules. Those are fine. They’re our job. Language always changes with use, and we can help it on its way. No, I’m referring to places where someone just plain didn’t learn the rule or got confused or overlooked it during the self-edits.