you can "swim up" the chain of comment parents until you find one that is at -3, and by downvoting that cause the entire downthread discussion to be effectively censored.
That only works when you have large discussions under downvoted comments, which should become much less common now.
Amusingly, this comment appears to be one such instance where a single downvote could remove a moderately large number of child comments.
I just found out that a new website feature was implemented 2 days ago. If a comment is voted to -4 or below, it and all replies and downstream comments from it will be hidden from Recent Comments, and further replies in that subthread will incur 5 karma points penalty. The hiding, but not karma penalty, applies retroactively to comments in that subthread posted before the -4 vote.
This seems to be worth a discussion post since most people are probably still voting things to below -3 without knowing the new consequences of doing so.