A possible solution would be to require one to solve a captcha, and to notify an admin, when someone downvotes more than 10 comments/​posts by the same author in a one-hour period (or something similar).
A possible solution would be to require one to solve a captcha, and to notify an admin, when someone downvotes more than 10 comments/​posts by the same author in a one-hour period (or something similar).