Planet13 - 7:34 am on Mar 9, 2012 (gmt 0)
For the same reason that people hereabouts lock out entire IP ranges or whole classes of browser--
yeah, but, that's google's job, isn't it? To find the good stuff amidst all the bad.
I mean, if they weren't doing that, then they could simply stop paying all their engineers astronautical sums of money to come up with the perfect algorithm, and instead just list irrelevant amazon and wikipeida pages at the top of the SERPs all the time.