Reading is how you develop critical judgment as a writer. There are books that may be written with a minimum of skill, but the story and characters are so interesting that it doesn't matter. This is a Truly Awful thing to realize, but I'm afraid it's so. And if you are getting words on paper, none of the rest of it is important. It's just that such things are subsidiary, and not in any way essential to learning to write.
Writing is as much a process of self-discovery as it is anything else.
To be successful, you need to know first what you want to write, and secondly, how to write it. Reading is one way of determining what you really want to write. This is basically a process of playing mind-games with yourself. Writing is largely a matter of persistence. No matter how bad you are to start with, if you keep doing it, you will get better.