4channer likely leaving out the part where it wasn't "everyone who disagrees with me" but actually just "Nazi scum" and he was offended. Nazis love to play the victim card publicly while wishing death on minorities in private.
Except Reddit bans you if you so much as suggest someone stubs their toe. The rules against "advocating violence" have become so broadly interpreted in the last few years.
Lemmy is significantly more tolerant of this kind of posting