On reddit you can not downvote comments from the user page. The downvote button ...

Houshalter on Feb 23, 2018 | parent | context | favorite | on: Hacker News's Undocumented Features and Behaviors

On reddit you can not downvote comments from the user page. The downvote button is there but it doesn't do anything. People who know this can get around it possibly, but it's stopped a lot of that.