And those giving it a 10, are also protest votes, only in the opposite direction. This would make the user vote perfectly valid. 
As for the so called GOTY awards, it could have a billion of them and it would still not change the fact that myself, and many others find that the game stinks.
not really, it just indicates how many haters and how many fanboys follows a game/company/franchise, it has nothing to do with the quality of the game itself. nobody with a sane mind trying to do a fair vote would give a 0 or a 10 for da:i. the average of these people doesnt become magically a fair score, because its just the average of people that want to troll or hype the game and nothing more. and to be honest, people with such a limited intelligence to see what kind of problem they cause with this behaviour cant be trusted and because there are a lot of it on metacritic the score cant be trusted.
i want a score based on the quality of a game and not a score based on dissapointed expectations, pure hate for a franchise or a company or blind following for a game. the internet (not only metacritic) is not the place for this. so the only thing you can trust is READ reviews or WATCH lets plays because there you see what a game does good and what not and you can decide how much impact these points have on your own fun of playing the game. yeah but reading and thinking is hard thing on the internet, better jump on a soulless score and ignore how much idiots in the one or other way can influence it.
and for the goty awards, when a game like da:i with millions of sold copies wins one of these, and a game like dos which only sold a few hundred thousands and is a pc only game is on place 3 it should tell you that the buyers of dos are way more satisfied with the product than da:i buyers. so not the qualty of a game decides a goty award, its more the range of people a game reaches, and how do you reach a lot of people? creating a hype. marketing and advertising wins an award, not the game itself.