And we shouldn't allow this concept to go unchallenged here on Lemmy.
Commenting on an active post is not brigading
Posting a link to something is not brigading
Commenting on something you were linked to is not brigading
The only thing that might be brigading, but isn't because it isn't a real thing, is someone explicitly going, "Hey everyone, go here and harass this person"
It's all fine and good that we have some new rules to keep the peace with other instances but we must fight against 
That's how the most of the internet works. The site admins of whatever community impose hegemonic rules about acceptable discourse and then purge everything outside that. It's how we work, it's just that we got rid of all the bigots and shitheads. In a normal community a landlord runs the instance, bans everyone who wants to shoot landlords, and tolerates bigots as long as they don't literally say the N word too many times in a row. Here the hegemony is flipped on it's head - Any kind of bigotry gets you banned fast, and you can actually name names when talking about why society sucks without having to pretend this isn't a knife fight to the death.
The difference is we understand why the conditions in other instances are the way they are, as you’ve laid out. and they think the conditions here are a bot farm, some kind of organized plot, or otherwise illegitimate
They can’t wrap their heads around it so they just yell cheaters!