You will never find a piece of writing that is so mind-bogglingly good that readers are willing to overlook bad grammar. It is enough of a reading impediment that bad grammar can disrupt the reader’s ability to follow an author’s train of thought. People trying to build up their writing skills tend to get quite lazy when learning grammar because it’s a lot of work and is more academic than creative. But once you learn the rules, it’ll be easier to retain that information and apply it in future writing.