We all know about the publisher drama and "bribes" and whatever the internet comes up with. But there is ONE thing that is persistent and is always present in video game reviews but big websites: The fact that the reviewer never bought the game in the first place.
As a consumer, I'd expect my $60 to be worth the purchase and get some quality entertainment from the game. On the other hand, the reviewer received a free copy of said game and probably never had big expectations from it, since they didn't spend a dime to buy it. They also never have buyers remorse, which is a common thing among gamers. They can give a game a huge score just because they can, and because they are reviewing a product they played for FREE.
Just my thoughts on the matter :)