The only point of these metascores are a dick measuring contest. Not worth stressing over.
They also tend to favour games with high demographic/lowest common denominator appeal, or obscure games that only get reviewed by those in their target audience. But semi-popular games built for a more specific audience tend to suffer - as, while they’ll get the high reviews from the target audience reviewers, they’ll also the mediocre scores from those who don’t really care about the game, or aren’t into the genre/mechanics.
A famous case: Shadow Hearts on PS2, which was poorly received because a number of sites and mags - mainstream sites like IGN, Gaming Age, Gamespit, and Next-Generation scored it in the 50s. But reviewers who liked historical RPGs, like RPGamer, scores it in the 95-100 range. Unfortunately, because all the mainstream sites and mags were reviewing it, the game averaged quite low, making it one of the most underrated games of the last 30 years. Had the game been less popular/hyped, it probably would have averaged significantly higher.