Riot stated that they are separating lore from gameplay not that it doesn't apply at all. I think anyone who thinks that removing the idea of summoners ruins the lore/gameplay in failing to see the bigger picture. If you think about it that was honestly an extremely weak thread that tied the two(lore & gameplay) together in the first place. All the champ backgrounds had this awesome development and then it was like "oh, now they have joined the league..." and it ended their story without room for development. All of their backgrounds were history and I think that Riot has decided to reboot the lore so they can actually evolve these characters over time.
If you watch their video "A New Dawn" I think this video clearly shows how the lore can play into the game. These characters can run into each other anywhere and have to fight it out. The claim that you don't care because Riot's lore has never lead Azir to the location you are playing him makes no sense. Could you imagine the horrible storytelling and weak threads that would have to be created to bring every character to every location? Just because the game mechanics are not a campaign doesn't mean that it doesn't work. That's like saying when Nintendo released Super Smash Brothers the lore of the Nintendo classics no longer mattered and made no one care.
To provide you with a great game the mechanics must have a start and end. But to provide you, or those who want more than a game, with an excellent experience they give you characters with depth, history and relationships. By eliminating the league from the lore they have also eliminated the dead ends that all of their characters stories had reached.
