Let me give an example of the kind of behavior that I think is being talked about.
Imagine, if you will, a fan of the Lord of the Rings books who is upset that the first Lord of the Rings movie did not include Tom Bombadil.
In any internet site that he frequents, whenever the Lord of the Rings movie is discussed, he will add his comment that he thinks it's a bad movie. Or rather, he will say that it is a bad movie as if it was an objective fact instead of presenting it as his opinion.
He will probably have a signature that makes disparaging comments about the Lord of the Rings movie, and the intellectual capacities of the writers, the directors, and the people who liked the movie, so that his dislike of the move is repeatedly referenced in every post that he makes.
In any thread which discusses the next two movies, he will post how bad the first movie was, and attempt to steer the conversation in a negative direction with questions like, "What are they going to ruin next?"
If he becomes aware that the directors or the writers of the Lord of the Rings movie are going to be involved in any other project, he will post comments explaining how they are terrible people and how he hopes that their project fails.
If any of the above seems vaguely plausible to you, then you have an inkling of the issues (real or perceived) that are behind the original blog post.
And remember, we are talking about fictional works here! At least in discussions about politics and economics, there are real lives and livelihoods which could be made better or worse depending on the final outcome arrived at.