That's exactly my point (see above). I think taking into account the manner in which /b/ is used compared to the other boards, one can hardly make the point tha

That's exactly my point (see above). I think taking into account the manner in which /b/ is used compared to the other boards, one can hardly make the point that 4chan is mostly /b/ - I'm surprised it has only 42%. Even if one were to make the assumption that all of /b/ is worthless, there is still a pretty decent amount of actual content left, and there are a lot of users engaging with it. I'd wager that even on a high-quality site like HN, more than 50% of all submissions are at 1 point or [dead]. At least 4chan has an officially sanctioned outlet for crap, keeping the majority of the boards pretty clean. /b/ is a necessary evil that's required for the (huge) rest of the site to function.