"Echo chambers"
Basically every space, offline or online, works a bit like a echo chamber. The majority tries to impose their opinions to the minority. At least forums are not created to be an echo chamber, like reddit is, with its upvotes and downvotes promoting the mainstream opinions.
"Moderators will throw the hammer to you"
While it's true that some forums have bad mods, I like strict mods. Mods are supposed to moderate, and too many people think that freedom of speech means that being disrespectful is acceptable.
"What is this accomplishing"
Socializing, getting advice, making friends and having fun with them, discussing specific themes and hobbies...