We Millenials consumed Gen X made media and Gen Xer's pop cultural was very "Its fun to be cruel to weaklings and weirdos, be against consumerist modern life dweebs, and swear in front of old ladies. We're so punk."
Gen X 90's culture being all about being a renegade nihilistic slacker as a reaction to the 80's culture which was a lot more colorful, consumerist, and earnest at an almost saccharine level, even when it was trying to "rebel".
EDIT: To clarify, Millenials consumed edgelord stuff from Gen X, and homophobia was edgey.
Breaking it down, the 'no' comes basically from "Free will doesn't exist so no one can justly be punished and violence just causes pain and a cycle of more violence"
The 'yes' comes from "We're all dead one day anyway and it is intrinsically pleasurable to harm/kill people who have wronged me, my loved ones, or any innocent people. "
The latter is actually a more unethical embrace of pleasure.
On a broader scale though I'm against both the death penalty and revenge/vigilante killing, but I actually think the latter is comparatively less unethical in a vacuum. At least in the case of revenge/vigilante killing someone is getting something out of it.