GPW: I have never followed any so called rules of photography and I have won a number of contests. photography is an art not squares and lines.
Good for you. With talent, you may find the most interesting compositions of a scene without using any rules. For most of us mortals, the rules generally improve the shots a lot.
Also, knowing the rules makes it easier to break them, while your winning shots could still obey the rules, you just do it by instinct. The other aspect is that of hundreds of entries, those shots that stand out (for example because they break the rules) are more likely to win. No one is saying these rules are everything.