Disqus also has the downvote option.
Had a lot of those on Bloody Disgusting. You could have a disagreement with someone about something. Then because the person got so aggitated,(s)he continues to downvote whatever you have to say in the future.
Then others start doing the same to the point it became ridiculous.
Example: got a lot of downvotes because I didn't on a racial issue so automatically I was a racist nazi Trump voting KKK'r.
Later on I said something like "Everyone's equal, racism is bad, Hitler was evil", no, not in sarcastic way. Same so called anti-racist people downvoted that comment.
Aside from that: downvoting is usually the weak and cowardly option.
"Durrrr. Words are hard. Clicking arrow easy."