The reason why you can upvote user comments is because they are (kind of) part of a rating system for comments; they do not bring any points that can be accumulated from other forms of upvotes. Usually, the most upvoted comments get to the top of the “best comments” section of an user’s comment history. Removed comments may not appear in any comment histories, even if upvoted.

For that little extra dose of dopamine while you game

Yes