Technically the game is non-canon, but the location could still be an actual place in Runeterra. And since it's not linked to a specific place, it's possible it actually has something to do with the kind of stuff you do in-game. Not specifically summoning the champions we all know, but the two factions warring, the towers guarding each base and nexus.
Twisted Treeline, Crystal Scar, Howling Abyss, and Butcher's Bridge are all name locations in the lore, and they DEFINITELY do not have minions, turrets, etc. in the actual world of Runeterra. But because Summoner's Rift is lore-agnostic, not linked to any current lore, it's certainly possible the "canon" version of it still has these kinds of things. Again, not the things we do in-game, but the location itself.