What the hell, Riot? Why is this bullshit allowed?

Just had a game where the enemy team grouped up the entire time, sticking to a single lane at a time, and still managed to match us for levels throughout the game. What. The. Fuck. Experience is shared between champions at a flat value? It doesn't scale down per champ present upon minion deaths? You can just ignore two of your three lanes for extended periods of time without any consequences? Is there no reason for having those other lanes in the first place? You can just do this sort of thing in any summoner's rift game and it'll work just fine? All these questions and more are what I'm left with after seeing this...fuckery, firsthand. I'm frustrated with how the match went, if you can't tell. #happyhappyjoyjoysong