One trick smurfing?

I already know that we love smurfs here in League and there's zero problems at all with smurfing and anyone should be able to beat any smurf regardless of rank just get good lel. /s Most of the time the argument I see is to "practice off roles" or "Play champs I don't know well." So then my question is: What about someone who smurfs and plays their One Trick champ? Like I just watched my friend play a game and there's a player on the enemy team who has the champ they're playing's name in their summoner name and has Mastery 7 with that champ and they aren't even level 30 yet. That's just what makes them look like a smurf, but they also even admitted to it. Are we okay with this too? I guess sure because they buy more skins still?