The statistical odds of having an afk or intentional feeder on your team is lower than the odds of having one on the opposing team as long as you never do it, four chances as opposed to five.
If you are stuck in lower ranks then it is because you are failing in some aspect.
When people are caught intentionally feeding they are inmediately issued a 14 day ban, with their next punishment being a permenant ban. Just report them and they will get what is coming.
The main issue with issueing intentional feeding bans is that a lot of people dont understand the word "intentional" which leads to a lot of false reports.
As for afk's, they are handled primarily by the leaver buster which gives people low priority queues for leaving too many games and if they keep it up for too long they get banned.
Personally I would like to see it work quicker but that would lead to people with temporary internet issues getting harsh punishments.