Personally, I think no to both points.
I liken it to people intentionally showing up somewhere they clearly don't want to be just to "boo" people minding their own business. See something in /all
you don't like and throw it a downvote? Whatever. But making a conscious effort to go in and/or consistently downvote stuff in that community is crossing a line, IMO. At that point, just block the community and move on.
Mods can't (currently?) do much about it, but on my own instance, I can detect that kind of activity with database scripts. They run on a schedule and, after a user hits a certain threshold of strictly negative "participation", the script will ban them from the community.