Edge...that's like asking for proof that things get wet when it rains.
The difference between 9/10 and 10/10 flat score is massive. Primarily because of the idiocy of scores in the first place. A 9/10 implies heavily that it's a good game, but with some context. The same way a 6/10 is abject failure to be avoided. A straight 10/10 implies perfection, which is an ideal to strive for, not a reality
And you know as well as I do that most people....and i mean that literally....MOST people do not read reviews. They only look at the score
It's simply the quid pro quo nature of the review industry. If those review sites want continued access to early copies of games, free copies of games, access to events and other special treatment from game producers, they have to grapple with the conflict of interests that creates.
I'm not saying that everyone does this. But enough do that it's an expected response that throws any "perfect" review into question. And it's as much the fault of the Producers as it is the reviewers who avail themselves of that special treatment. Blackisting and playing favorites, giving early copies of games to sites that give favorable reviews.
Even a reviewer with honest intentions would feel that pressure. And staying objective in that environment isnthe exception, not the rule. Combine that with obvious cherry-picked review scores.....
...I guess mostly what I'm saying is very similar to what you're saying:
Actually read the reviews. Don't use scores as a measure of anything. Be aware of the atmosphere of bias. Carefully consider and form your own opinion based in multiple sources, and don't let other people make the decision for you.
And to the other point: Using these reviews as evidence to support an argument of whether the game is good or not is....questionable, at best. It's to subjective.