Oh, then all off topic posts should be banned?

No - people who obsess about the death of Carrara on the Carrara forum are intentionally trying to sow discord. That is not the intent of every off topic post.

definition - internet forum troll

In Internet slang, a troll (/ˈtroʊl/, /ˈtrɒl/) is a person who sows discord on the Internet by starting arguments or upsetting people, by posting inflammatory, extraneous, or off-topic messages in an online community (such as a newsgroup, forum, chat room, or blog) with the intent of provoking readers into an emotional ...