One of the biggest problems in game curation, aside from declining quality control, is review bombing. If you don’t know what that is, it’s when angry gamers band together to attack a game or other piece of media, for reasons that are probably shallow at best, and spam negative reviews. They also upvote each other’s reviews to make sure those negative reviews all rise to the top. Steam is attempting to fight this and provides context, as well as a new addition to the system, in a recent update.
Ultimately, Steam is disturbed by the practice, as it damages the overall accuracy of user reviews. Steam uses user reviews as its primary metric for discoverability. When you look at a game, one of the first things you’ll see is a label based on the overall review scores. That said, Steam also says in its statement that despite review bombs being annoying and extremely lame (my words), they don’t usually hurt the game’s scores in the long term. Either the reviews come back up over time, as legitimate players come through, or the reviews stay low anyways, for the same reason.
Steam doesn’t want to mess around with the actual reviews too much, as it feels like that would do more damage to other parts of the Steam ecosystem. Therefore, instead of changing or removing, the company added a new feature. Now, when you look at user reviews on Steam, you can access charts that show the user reviews broken down over time. Now you can visualize a review bomb, and savvy players should be able to identify it as much.
Source: Steam Community