I've had a this conversation a faasand times,
Warrior Cats, like all vermin, are conceived often and very quickly.
The average Warrior cat female with a furrism zygote takes 30 minutes to write up to 2 sniveling, whimpering children, which grow up into additional stories, which take minimal time and effort to write. The stories of the civilized folk take much time and much effort to create, and thus, there are more vermin than there are proper stories.