If Summoners are non canonical now, why is it still called Summoner's Rift?

So since Summoners haven't been involved in League for how ever many years as it has been now, why is the rift still called Summoner's Rift? Why is there a Champion Remix about Sona where the refrain is one of her unchanged in game lines about only the summoner being able to hear her? Why does Brolof ask the summoner to summon hot chicks for him in game if summoners don't exist anymore? Seems pretty lazy to me to retcon summoners from the lore, but still leave bread crumbs of their existence all over Runeterra.