So I've experienced this multiple times, where the player on my team intentionally feeds and even admits to it in chat. Then I get mad and get banned for getting mad, yet they get a slap on the wrist with a warning if even that. Seems like a pretty garbage system to me. And to be fair many of the things that I have said while getting mad are low grade at best, the standard of what they seem to think is bad enough to get banned for is also garbage.
So in my mind I feel like actions speak louder than words, but it isn't the case here at Riot.