There's so many variables beyond dmg/heals/deaths in this game though. Would a rdm that gets amazing dps but doesn't throw out support when needed be a higher rank than one who can react to changing situations better with slightly lower dps? How about a player who can bait mechanics or prioritize targets better? I'm reminded of Overwatch matches where a match was lost due people chasing gold medal for kills but not playing the objective (and those golds being in single digits cause of the unending 1v2+)

On top of needing a stupidly fine-tuned grading system in the backend, this would only further segregate the queues and slow down DF. In an extreme scenario (while highly unlikely) players may even perform worse than they can to stay in a lower tier for faster queues despite the risks.