When you realize Blizzard and Riot are the same company
Blizzard - Let's shut down Nostalrius because players don't like our game the way we made it and that upsets us. Also, lets not take all the money they want to throw at us for legacy servers! That would be bad!
Riot - Let's just keep ignoring the community.... oh wait, this isn't working. New plan! Let's take one money brick out of this money castle and use it for something.... no? Oh wait, I have an idea! We already pay these guys to do work... let's just have them come up with a similar system to another MOBA in which game modes rotate based on a timer. Hmm.... but we can't have them available all the time or else people would have fun and enjoy our game. OH! BETTER IDEA! Let's bring back URF, and lets make it only last TWO DAYS! Then let's make every other mode last a week! Brilliant! Let's just not make a second ARAM queue that is URF on Howling Abyss. That would like, let people enjoy the game or something. We're totally not about that. Are we starting to sound worse than our competitors yet? No? OK, we'll keep working on that.