"Our system matches smurfs against other smurfs"

The "Smurfs vs other smurfs" is for low level accounts. By level 5-8 or so you'll be playing almost exclusively with other smurfs/perma banned players leveling up. It has nothing to do with ranked, it's simply to separate smurfs from new players while leveling up. Smurfs don't enjoy newbies running into towers repeatedly, building nonsense, having no idea what to do - And newbies don't enjoy smurfs stomping them, flaming them, etc while they're just trying to learn the game.

That smurf rule only really applies to games where people are just starting out.

Ranked is still bound to the ranked rules of match-making above all else. It's not going to throw someone in Diamond/Master/Challenger right away. They have to climb like everyone else.

It doesn't apply to ranked.

Or you could just stop perma-banning accounts for calling people shitters in-game and have them perma-muted.

Over night, 90+% of smurfs would disappear.

Gj taking riot's words out of context.