So far I've only played 19 games of ARURF. 15 win, 4 losses (Bragging). One game had an 'ez' spammer. Two games had the opposing team fighting in /all. 5 games had 'GG EZ' as the games ended. I didn't encounter too much toxicity so far.
It's not trolling to leave a lane with a bad matchup to face a champion that your champion can deal with, or roam for ganks, or group to push turrets. Those things help you win.
My team won a game laning 3-1-1 from the very beginning. The Singed didn't want to go botlane, and a duo wanted to lane together, so they laned as a trio. The duo did spam ping him for a minute at the start, but calmed down and got to work once the game started. I did give up first blood solo in the botlane against an Ahri/Nautilus combo as Graves. Singed would have been fish-bait trying to lane with me, but the pressure of a trio top-lane kept him safe. I played safe (after FB fml), farmed up, eventually won lane, then we grouped for objectives and pushed for the win. It would have been much more difficult if we had people arguing in chat.