You probably haven't spent enough time here to know how this works.
There are several levels for popular shows for /a/, and its easy to tell where a poster fits by their comments.
The Disenfranchised- Former fans, that upon seeing series that have actual writing instead of pandering to the demographics that they were made for. Or, even better, doing both at the same time(Baccano is an example).
The Haters- These people haven't read Naruto because they assume they know what is within each chapter before they read it. If they have an ounce of reason, they are right. May have a dislike for the fanbase itself.
The Secret Lovers- One Piece has a lot of these, they will either openly state love for a well-established series that is defamed by Haters. They can also masquerade as Haters and post in these threads, acting like they hate the source material but still reading it on the side.
Chances are that every series on /a/ will eventually devolve all commentary into one of these three categories, despite claims of personal opinion or being free of the hivemind.