What forums are those? Because this isn't the case with the forums I frequent. The boards I read / participate in tend to operate on the principle of "don't make me come over there", and everything is reactive, not proactive. I'm not sure how you'd get things like "user was banned for this post" etc otherwise...
I don't have a problem with moderation being delayed. I have a problem with there being no moderation or clueless moderation (I have reported hundreds of obviously fake accounts or pages promoting outright illegal activity, and the majority of those got ignored).
Of course, the scale was much smaller than Facebook, but my point is that maybe if you can't solve this problem then you shouldn't be in a position to broadcast & promote stuff to the entire world? The danger of Facebook (& other social networks) isn't in your friends seeing your malicious post, it's that your malicious post can go "viral" and be put in front of people who haven't asked for anything since the ranking algorithm is based on stuff like "likes", shares, etc (and a lot of garbage content tends to attract likes unfortunately) which can also be manipulated by a determined attacker (using fake/compromised accounts to "like" the post, etc).
Nothing is visible until it's been validated. Guardian comments still do this for some topics.
With all the assorted profiling going on, I'm sure just as some users (like via Tor or VPN) are automatically given harder Google captchas, or some boards make you earn enough karma to perform certain actions, reactionary moderating could be something you have to earn, and sustain. Perhaps certain interests would trigger proactive moderating too.
Not perfect but certainly capable of taking much load off human moderators.
Forums have managed to keep undesirable content at bay with often no budget at all, so anyone claiming Facebook can’t do the same is false. They don’t want to do it, because abusive content still brings them clicks and ad impressions (remember that for every nasty piece of content that turns into a PR disaster there are thousands that go unnoticed but still generate money for them).