That would be a dangerous game. Who would be in control of such a system?
The publishers? Hell no! They'll take any ability to give them to stamp out anything less then a pefect 10.
A neutral third party? They wouldn't stay neutral for long.
Consumers? They're ill equipt.
Just remember, one persons reasonable reivew is another persons "outragous click-bait"
And I echo other sentiments that metacritic isn't he problem, just how people use metacritic. I learned a long time ago that an averaged number based on EVERYONE'S reviews isn't a useful to me as the opinions of two or three critics whom I know think along similar lines to me, who I can follow and get the information I need.