User blog comment:A.Darkbloom/Institute of War/Summoners/etc no longer being canon/@comment-12049719-20140906031129/@comment-12049719-20140906130141

"...only existing to amuse the player"

Well, that's just the point. League of Legends is ultimately a MOBA game created for the amusement of several people. The lore is there to give each champion a background. What their lives were like, where they came from, etc. If it's gonna be stuck as the whole Summoner-Champion lore, there will be inconsistencies with other lores and expansions would be limited. Let's face it, not every person/creature in Runeterra would have a reason to join a place where they are controlled by the God-like summoners to settle their differences.

Take Lucian and Thresh for example. Thresh stole Lucian's wife's soul. Now he wants to hunt him down. Lucian finds out Thresh is in the League (for some reason) And so, he joins, kills him, and leaves. If that were to happen, then Thresh Lucian's presence in the game would be non-canonical because Thresh is dead and Lucian isn't in the League anymore. If the lore stays the same, then conclusions to their stories can never be reached.

This is the reason why gameplay and lore should be separate.