I think smurfs that do that kind of thing are a minority, like when this account gets to level 30 I wouldn't go out of my way to ruin a game for others. I also wouldn't say I'm a smurf to my team. I play an off role on this account and I'd play ranked just to see what elo I am at the role. There are probably more smurfs in your games than you think, if you check their op.gg's and they only play ranked and they're level 30-50 with no rank in season 6 or before, it's probably a smurf
Players that get permabanned and are toxic on their new account are frustrating because they're toxic as hell until they get a 14 day ban, so I'd just report them, leave some description in the box and you'll relieve the burden from other players.
Most smurfs want to win!