The main problem for rating games and other entertainment things is, that there is no universal scale in several directions. You have the spectrum of production value. And very important, the nieches, genres and topics a game deals with.
If you can't stand platformer games and can't stand medieval fantasy, such a fantasy platformer could be from a AAA studio with dedicated and caring developers and you probably would still go: meh. 1/5 Would not play again. And if you are a fan of both a half hearted attempt by an amateur that made you chuckle could be 5/5 Made me laugh.
And even with fans of something, they might be the harshest critiques. As an example, Darkest Dungeon was a masterpiece. Darkest Dungeon II is a steaming pile of crap, despite higher production value. Why? Because they missed the target audience they built up with the first game. They changed the genre and disappointed. On it's own as an original game, it might be good.
A stark contrast is Monster Train and Monster Train 2. They hit the target audience spot on.
Ok, those were sequels, but the general point is hitting or attracting the right players. If you attract players to a game and they are disappointed, they will rate it down for wasting their time. Like announcing a psychological horror game and it turns out to be a slasher horror game. Or boasing beatiful graphics, and it is just AI with high resolution.
With large numbers, it should even out since mostly the people interested in a genre would rate, so the rating would be somewhat accurate and compareable. And that's whats important, imho. Does not matter if it is stars or other systems.