Use of these services often involves providing URLs to non-official third parties, which can lead to data privacy issues or account flagging.

Increase social proof or visibility of a specific message in the comments.

While it can boost visibility, YouTube's actual payouts are driven by views and ad engagement, not comment metrics.

: Comment likes are often purchased to "pin" a comment to the top of the comment section (as highly-liked comments are prioritized by the algorithm), which can be used to promote a link, product, or specific viewpoint.