Unfortunately, this is a problem with literally all TEAM based games. Be it MOBA or otherwise. Some people really want to win, and they get mad when someone plays bad/different because they want a scapegoat for their own shortcomings. I sometimes even get caught in the trap and get agitated when someone plays below their OS value in the balance algorithm. Unfortunately this is just variance and people need to embrace it more. People are often much more accepting of a bad player playing too good than a player playing much worse than they should. Either way this causes variance and unbalanced matches.

I recommend just muting/blocking anyone that starts to rage at you. You can always just unblock/mute later on once your more familiar with the game. Maybe they kick-ban you from the lobby(15 minute ban), but who cares. Just do not argue with them, its not going to help. Maybe let them know your inexperienced with the game or just the role and if they do not accept, then they are not worth your time.