I am not sure what this is about.
Is this about comments on games? It is a standard feature in social media like interaction. Community threads even had that, but it was removed for various reasons.
In game commenting it still has a benefit. If someone posts something opinionated, people can express agreement or disagreement with said opinion. Instead of posting their own opinion below it. There is the silent users, that do not post, like ever. If someone posts crap, you can still voice your disagreement, without exposing yourself to the troll.
Also, as a new user to a game, if you browse the comments and look at up and down votes you can get a grasp how the general disposition of the regular users might be.
If comments are getting out of hand, it is possible for the dev to switch the comment mode, like notime explained.