There is a risk indeed. You can nevertheless enjoy such a "mainstream" game and give it a high score if it's exactly what you want to play. There is nothing wrong with that.
There is a lot wrong with that, to an extreme (mainstream games generally have payed reviews), when you give a game which was compromised in order to appeal a high score, and you give a game which has actual thought put into it's design and respects the player as someone with a functional brain a low score. Do I really have to explain this to someone? Reviews dictate public opinion, 90% of all reviews are purchased marketing, those that aren't are generally given much lower scores, despite the objective superior aspects of the genuine game. Given that reviews dictate public opinion, they also dictate the perception of publishers which have a role to fund games, they will refuse to fund games with lower scores, because the public doesn't like them as much, because the reviews aren't as glowing. So we get less good games, this is why the industry was nearly creatively dead up until kickstarter shined a light of hope on us, which was promptly tarnished due to scammers, which made the internet collectively go "lol kickstarter game, must be a scam". Cause and effect chief, start living in the real world.