Yeah. It is against the rules not to compete. If you do not submit a song, the moderators will disqualify your non-entry.
Just joking. Chill man.
There is no such thing as not good enough. I have never even got close to a first place, but that does not matter. I do it for the fun and for the challenge. I need something to motivate me to get off my backside and play something. These contests are wonderful motivators, and besides, the feedback you get from the other participants is worth gold.