graeme_p - 12:06 pm on Aug 19, 2013 (gmt 0)
Zurish, that explanation does not really convince me.
Lots of small information sites run adsense.
Lots of big sites use other ad networks, or sell ads directly. Even if they use adsense they can extract better terms than small advertisers can.
I think its driven by fear of web spam. Google have lost the batter to such an extent that they are trying to send people to known safe sites.