Some potential solutions to the new player experience

A smurf only queue. Give it some kind of benefit so that smurfs will want to use it.

Allow players to register smurfs under the same email as their main, and of you do and have a level thirty main then let those players pay rp or ip on order to instantly level a smurf to thirty.

Queue normals games based on mmr and ignore summoner level. Every ten levels, reset the normal mmr of that player to easily separate player skill.

Eliminate summoner levels altogether and always match through mmr.