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 
r/CTH was constantly accused of brigading for the same reason Hexbear is now constantly accused of brigading. We've inherited high posting activity from CTH, and now that we're federated we have the ability to see posts from and comment to other instances. That's it. They are basically complaining that we post too much and that we disagree with them, then they equate that to brigading.
It happened all the time to users on r/CTH who happened to use other subreddits. We'd be accused of brigading just for having a history of posting in r/CTH while posting normally in other subreddits. Accusations of brigading should be entirely dismissed unless there exists evidence of organization with the intent to swarm a particular community.