The history of 4chan is always whitewashed/demonised depending on what point you want to make. Moot is not a saint and not the victim he's trying to paint himself to be.
As to 4chan itself, it's a message board - it's the people that used it that have done all these things and if 4chan goes away people will just move to 8chan or other places so all this agonising over whether or not to censor/shut it down is pointless.
The thing is that most people here will agree with you that its the posters responsibility what content they upload. But the law says otherwise, at least in my country and I guess in the US as well.
Providers are safe carrying most content as long as they comply with legal requests as they come in and aren't actively conspiring to keep illegal content up. The only thing you're required to proactively report and delete is child pornography.
As to 4chan itself, it's a message board - it's the people that used it that have done all these things and if 4chan goes away people will just move to 8chan or other places so all this agonising over whether or not to censor/shut it down is pointless.