Problem is that this would penalise certain playstyles. It's very possible that someone was important for the win by bumping, making passes, etc but that they get less score than the people making the actual goal. Giving them less rating would make things worse and just isn't fair.
#MMR Fix
sharp vault
Pretty much any artificial measuring we do of 'performance' will never be perfect, especially as the meta evolves
stuck scarab
"luck" as in a magical tendency to consistently have above average outcomes to random events isn't a thing that exists. Matchmaking as a random event isn't putting noobs in higher rank through luck, a win is like 10ish elo and you need more than 100 to be put in a rank you don't deserve. If mm putting you in a team so strong that you'll get carried happens even half the time, 2^10 is 1000 so that's unlucky to happen based on luck alone