If someone rallied a hate-mob on 4chan, though, how would people know?

Since 4chan overtly resists it, it'd rapidly move off of there, but it's still a great place to find like-minded folks that'd follow someone to another server to go brigade someone.

4chan has always claimed to resist it, but 4chan was never immune to being shuffled a specific way.

Right, “not your personal army” was a quick way to decline to advance whatever doxx was being requested at that moment. Not an actual ethos. They regularly doxxed and swatted all sorts of people.

Immune is the extreme.

"claimed to resist but hasn't been immune" is reduction to absurd.