Players who make "Friends" on the enemy team

Seriously, I would rather have an intentional feeder. Last game I played our Lux was telling the enemy team everywhere we were, what we were doing, when we were ganking. Just because she decided from... like minute 1 that she liked their Talon. Thus ruining the entire game for everyone else, and assuring our defeat. She seemed to think that because he did not kill her and let her farm, that it was okay.

If you think this is funny, it's not. It wastes 20-45 minutes of people's time and makes them very mad. On top of that, I hope these kind of people get banned over even feeders. Because that is insane levels of lack of consideration, and destruction of the gameplay. Sometimes I wonder if disabling all chat would be the solution, since it feels like nobody gets ban despite reports. And it's not rare enough, I run into an intentionally feeder 1/10 games, I run into a "buddy buddy" who helps the enemy team about the same.

Had somebody just log off and quit playing with me because of it. That is lost game time for Riot, lost sales potential, and more angry opinions about the game. So to me it is just as valid as any other toxic attribute of the community, except hacking, discrimination and death threats.