Certainly there are ways to thwart it technically, and those should be implemented.
It's tricky because "Followers only" is also a valuable feature many people use for good purposes.
Plus, anything that requires system changes competes for priority with other things like quote-posts.
BUT, one thing that could certainly be done is to name it (Brigading), define it and make it clear that doing it is a ban-able offense. Encourage people to send screenshots to the mods.
