A player I had the 
of being grouped with sat in base when my other teammate called him bad, throwing the game.
I did the "right" thing and reported him after game without responding in kind.
Yet he's still playing unpunished after being very toxic and soft-afking a ranked game.
The report system is automated one report won’t really do anything but like 50? They will probably get banned
Leavers and afkers are punished by the LeaverBuster system, which results in a Low Priority Queue being placed on their account. All that means is they can still play, but they have to wait up to 20 minutes in "low priority" before they are matched with a team. Only the most egregious cases are escalated to manual review for possible suspensions (as in, leaving many games over a long period of time).
If they were attempting to skirt the leaver/afk system, then it may be looked at harsher than if they were just sitting there afking. Riot would have to manually review that though, which takes time.
I had an anivia follow me around and take all my jungle camps and support said "while we can see she did her best to ruin your game, telling her to 'leave me a lone and go back to your lane' was not called for and that is why you are being punished." Also, support told me "we see they were doing their best to ruin your game" they were never punished and played for hours after and played the next day just the same. What a joke.
