Time factor:
There's people who literally can't play their role / new to the game and are basically worth almost as much as an afk in ranked.
People who literally know that the game is a flat out loss despite the majority of people in their team unable to understand how they have a low chance of winning.
It's unfortunate, but you have this occurrence of people who refuse to surrender a future 40 minute loss that have no skill vs. the game theory of needing to FF low win % games. "Playing it out" is a waste of time for some games in ranked, especially if you have a terrible team comp that has a bunch of fed enemy carries in every lane. Since low elo has a hard time closing out and/or they farm KDA, this means you're spending another game length times worth doing nothing but getting killed along with your stats. If the player has a disposable account (even a smurf) they can just throw it hard/afk and win the next 5 without a problem in 20 minutes each. I don't condone this behavior, its just what makes sense for those players.
The sophomoric culture upheld and the smurf question:
There's no real barriers to ranked and players with a low understanding / mastery / experience commonly ruin games. They are typically leveled in ARAM and the general toxic culture of new accounts makes them report everything while literally soft-griefing every game they exist in. Nearly every old veteran of ranked regrets getting into ranked too early, but nothing was particularly done about things to keep pure noobs from trashing default MMR are climbing. Honestly low barriers panders to smurfs more than real players as there's less investment in an account to play. That's a problem because you have a bunch of players that aren't invested in the account rank and will just start over after probably trolling "bad players" until their high LP gains run out. You are left with a LOT of
and other KDA sounding mainer players who think they are good/above avg (yeah its that effect) but just lose without anything invested or understanding a team game. First season of flex was basically ruined without having a good team as it was flooded with solo gold 5 scrubs literally calling it normals and just messing around.
I don't know why rito is chat banning salty junglers with their S8 report algorithm changes when the structure of the unpleasant part of ranked has been left relatively unchanged.