For many people the arguments and the information may be meaningful and even new. For example, you already learned that if someone is telling another one that he/she likes teenagers it's not an accusation of being a pedophile because the ephebophilia and pedophilia are different psychological phenomenons.
Some people even don't know that not only adults may legally have sexual activity but also all of the non-adults who are already 14+ (the age of consent in China and many other countries) or 16+ (Philippines, Japan), 15+ (Thailand), etc.
Locking a topic prevents new users or existing ones to add up to the forum's content (which is its only capital), needless to say it's a totalitarian method used by the censorship in the freedom lacking societies like Russia (Pussia) and China (Xina).
Limiting the freedom of speech and expression can't be "for good".