Pffffffft you had me spitting out lung juice XD. Anyways, wow I agree with what you're implying. Why does this exist? I have no idea, but I do have a theory: Maybe they are trying to connect themselves to something that seems so bonding, so family-like, because they themselves do not have any friends, craving for the companionship and loyalty that is so evident throughout the book series.
However, their obsession with the series makes people want to avoid them even more and so grows their need for intimacy. This makes them more obsessed with WC, because it's the closest thing they have to fill the void of friendlessness. Of course, due to the internet, they can connect with other people with common interest. This makes it harder to stop, because finally they have people they can talk to that actually have something in common with themselves. Not to mention that these people make this obsession seem like a more positive thing, thus strengthening their obsession. This creates a fanbase that keeps on going, drifting away from reality more and more until it starts getting out of hands
Maybe this Warrior Cat thing is something greater than it is. Maybe it's a real-life metaphor for how all of us get into groups to satisfy our need for intimacy despite how ridiculous the thing that brings us together. Maybe we can learn from this experience to help better our awareness about the type of people that we associate with, so that we can all live a happier and more fulfilling life full of people who actually care about us.
Or maybe I'm just looking into this too much. In that case, don't mind me. I'm just rambling by this point.