In an admin post at the top of the board, Poole (better known by his anon handle "moot") laid out the rules and reasoning thus:
this board was created to get the fifty million "HURR DURR RATE ME / FUCK SMOKE FIGHT / AM I PRETTY /b/????????" etc threads out of /b/. it isn't a camwhore/porn dump board, nor is it /r9k2/. keep the baww threads out of here.
use this board to do the rate-me threads, local meetups, report in, etc. keep it out of /b/.
Makes sense, but it's still a sudden and unlikely move for moot, for a couple of reasons. One, moot is not known for his propensity for making changes to his site; really, one of the beautiful things about 4chan is its still based on a platform virtually unchanged since 1997 -- clean, simple, easy. Plus, /b/ tends to hate change anyway, as evidenced by continued bitching about captcha. Two, /b/ is incredibly cancer-ridden, and that's pretty much unavoidable -- precisely because of the other beautiful thing about it, which is that it's heavily trafficked; the sheer amount of posts makes it impossible to keep up with.
Nevertheless, whether through an uber-rare instance of anon cooperation with anything or through increased administrative vigilance, the /soc/ board so far has done exactly what it's meant to do. Since Sunday, the board has been basically absent of rate-me threads and other such derpery. Which does make /b/ a somewhat more pleasant place to be, if you can call /b/ pleasant in any sense of that word.
Which kind of brings us to our last point, which is just that: When it comes to /b/, getting rid of "do you leik me" threads is kind of like dumping a bucket of bleach into a kiddie pool full of shit -- it's maybe somewhat more sterile, but that doesn't make it any less awful.
That said, in b4 "rulez 1 and 2," assholes.