Firstly, Riot is wholeheartedly against the concept of a Prisoner's Island. They want players to be able to reform, and throwing someone into matches with several other toxic players would give them no incentive to reform - they may either just continue being toxic, or quit playing entirely. Allowing punished/reported players to play in the non-toxic playerbase does have its own risks, but it's significantly more likely to result in reform if the players are actually playing with decent human beings.
Beyond that, though...
...and give them one rule to get out from there win 10 games at row.
This really has nothing to do with toxicity or player behavior. Granted, being toxic does ultimately reduce your chances of success, but...Win ten matches in a row to prove you're not toxic? Pardon if I come off as harsh, but that makes zero sense whatsoever.
Toxicity isn't about winning games, it's about behavior. You can be skilled and toxic at the same time - you can also be shit at the game and be toxic. In the same vein, you can be sportsmanlike and skillful, and you can also be terrible and still sportsmanlike. The point being, you can't use bare surface-level player skill to determine their behavior.
And, lastly:
...and those people would have their own little heaven of flaming,toxic,afk,sprouting nonsenses,blaming etc
The goal of punishments (up until a permaban) is to encourage the player to reform and stop being an asshole, not to accommodate assholes by giving them a toxic safe space. It'd be better to permaban them from the game outright than sequester them to their own queue to run rampant in - and to ruin the games of potential light-offenders.
