My friend has died, on average, every 2.6 minutes his past 10 matches. He's also had the absurd luck of his teams covering for his feeding, resulting in wins. Tell me how it is remotely fair for someone like that to get 5X the points of someone on the opposite side of the coin, doing everything in their power to carry a team of failures, only to end up losing because they just couldn't do enough.
Valuing winning is one thing, but when someone can perform horribly and yet get 5X more points than any player on the losing team that's not even remotely right. For example, I barely won a 5v4 that the enemy Ekko nearly carried for them singlehandedly. Even if I feel I did my share of carrying for my team, I think he should've at least been somewhere near the same ballpark points wise.
Some matches simply are not winnable. Some matches it's you and maybe one other person who's competent trying to carry a bunch of dead weights and failing. They either need to make it so the difference between winning and losing is less in general or so, if you earn (for instance) an S- while the rest of your team were Cs or or below, you get a slight boost in points compared to your teammates.