You know a lot arguments start and revolve around the subject that one player is better, they dispute witch one is actually right, so what do you think of a 1vs1 one lane mode vs players and AI, so they can stop arguing and go settle it themselves after.
It would also help if we had more daily quests, maybe some mini games like whack a Viking? Abathur Tunnel Maze? Falstad Coin Race?
Daily login with rewards increasing by day and daily quests and things to do.
This would also make the players more happy and happy players are unlikely to be toxic. They can also play the mini games alone obviously granting them some cooling off me-time.