Before you read half of my post and start rage typing your comments, please at least read the whole thing. I've seen (and experienced myself) the anger and annoyance of how snowbally league has become, and I feel like I have found the solution. If they removed the gold granted from killing another player, like 90% of the snowballing in league would disappear. It would also put more emphasis on objectives. Say you kill your laner, instead of getting the gold from killing them, you would have to focus more on capitalizing on their death i.e. shoving waves, cs lead, getting objectives. This would allow for people to comeback, as they would simply need to just outplay their opponent, rather than have a gold --> stat deficit that makes it mathematically impossible for them to defeat their opponent. Additionally, this would require the player ahead to consistently play better than their opponent, since the opponent has plenty of opportunity to catch up. Also, often times your team member(s) get ahead and start playing sloppy, thinking "I'm ahead they can't stop me" and causing them to throw the game. This I feel would decrease the amount of players who get kill greed, and the "I'm ahead I can play sloppy" mentality that often ruins games for the people who are on the "Carrying/Fed" person's team.
TLDR: removing the gold granted for a kill would require players to consistently outplay their opponent while allowing the opponent to comeback, decreasing snowballing