Why doesn't Riot ban botters?

I am a casual player who mostly plays TFT, ARAM and Coop vs AI for missions. Lately I cannot play a single AI game without having bots on my team. Today I had only one human teammate and 3 botters who kept running it down and feeding. It is cheating as far as I know but even if it is not, intentional feeding is against the rules for sure. So why doesn't Riot permaban these accounts immediately? Don't tell me they do because if they did then they all would be below lvl 10 and not around lvl 30. I played almost 20 years old games that have the feature to autoban botters. How the hell is Riot unable to do so?
Best New

We're testing a new feature that gives the option to view discussion comments in chronological order. Some testers have pointed out situations in which they feel a linear view could be helpful, so we'd like see how you guys make use of it.

Report as:
Offensive Spam Harassment Incorrect Board