I believe that the only way to counter concerted trolling/discourse control is by heavy human moderation in combination with IP banning and eventually even shad

I believe that the only way to counter concerted trolling/discourse control is by heavy human moderation in combination with IP banning and eventually even shadow-banning. As Slashdot is in my opinion illustrating, merely having a decent moderation and meta-moderation system might not be enough. You need to permban IPs of identified trolls, and in the end it doesn't matter whether these are part of a concerted effort or just individuals who post toxic content. Hobby researchers on Reddit have found out that they were able to push a story to the frontpage by spending a very low amount of money (about 200 USD if I remember correctly) for some puppet accounts and making sure that the very early moderation upvotes their story and downvotes critique. That gives us an idea how hard it is to counter concerted efforts of influencing discussions.