There's just not enough user posts on meta-critic to consider them statistically significant. When meta-critic first came out it was very 'edgy' because it was a good alternative to online and print reviews that seemingly were mind-blowingly purchased by publishers. At this point it is just interesting, not definitive.
How often is there a game with 30+ user reviews from just owners? Not often. So it's usually just a small sample pool, mostly just qualitatively useful when a user gives strong criticisms with examples.
It's still a good way of finding different opinions, especially from indie journalists, but it isn't a particularly convincing algorithm for determining that something is 'good' or not. For a gamer, the most interesting thing about meta-critic is the classic list of must have games that have scored over 90 points in professional reviews, yet a lot of those games and reviews are many years old. Go figure.