Believe it or not, Topic's that are simply breaking the rules get deleted yes. But they certainly don't get deleted because the mods are evil or bored.
The fact is most topics get deleted simply because they are in the wrong bored. Like a topic about Annie being OP in the Player Behavior forum is certainly out of place and thus gets deleted. User's who have topic's deleted for this reason are not issued a warning or suspension and are instead simply redirected to the proper form and told to try reposting their topic there instead.
Why Mod's can't simply move topics though is beyond me, every forum software i have ever been on has always allowed moderators to move topics to the proper forum without deleting them. Why LoL boards can't do it I have no idea.
Regardless I hope that she'd some light.