Smurfing isn't, shouldn't be, and never will be a punishable offense. If a player has a new friend they want to teach, they shouldn't have to force the newcomer into a level 30 game. If a player is Plat with Bronze friends, same thing. And then there's WildTurtle, who usually has multiple challenger accounts. Should he be denied that fun? You can disagree with all of this. We're all entitled to our opinions.
Smurfing will happen. You'll get carried by them, you'll lose to them. Regularly used smurfs will climb the ladder fast. You won't see them twice. If it's an account that's rarely used... well there you go. You still won't see it twice.
A ranked restriction for smurfing... how could you honestly tell a smurf from a player having a good game? I've carried on champs to the point that I look like a smurf in Silver. No, I'm actually Silver. I don't want to get punished for carrying consistently. Matchmaking/MMR will already do that.
Yeah, MMR. When you win enough games, your MMR goes up. Sometimes, it skyrockets, to the point that you get matched with people too good for you. Then it takes a few more games to balance out. I don't need to be reported for matchmaking to do what it's gonna do anyway.
The real problem here? Sounds like you've lost to a smurf. Maybe not once, maybe not twice. Frequently enough to post about. But how many times have you had a smurf on your team? How many times have you beaten a smurf who was over-confidently trying to solo carry?