There's usually atleast one of these mass-gore/research rampages a year, sometimes a couple.
Most of the time they just come out of the blue.
There was one a few years ago where someone just posted page-stretching images of someone tossing themselves off on a large number of topics.
Admins usually get on to it pretty sharpish and clean it all up. Don't normally get any repeat offenders in the form of Alts.
Blocking someone from posting following repeated reporting is a bit awkward.
It would be too easy for someone to go around and just report loads of posts for one person, or for a whole group of people to do it to stop anyone they don't like from posting.
And I'm sure there are probably some reports that completely escape the Moderation team, so it would be kind of unfair if someone was essentially banned until a moderator can get to them, which might never happen.
It's a nice idea and would have a good basis in an entirely trustworthy community, but I don't think those really exist, and it would likely just be abusive.