User blog comment:Reilock/Riots new Lore Direction: Rant/@comment-24801497-20140926174351

RiotRunaan had something to say shortly after these lore changes were made. Picking out one paragraph, because it's a very important one.

"Another part of the answer is that ending the League wouldn't fully remove our ties to it in terms of storytelling – characters will have still interacted with it in the past, the “fall” of the League would still be significant enough to deeply influence all of our champions' lives, and “summoners” would still be a dangling, confusing story piece we'd have to deal with somehow."

So while the League is no longer canon, that does NOT mean that it, and the Institute, and Summoners, have never existed.