If I buy your vote, are you coming to my blog to look, or are you getting paid to look away?

Centralization of SP. If you have a bidbot and 1000 people delegate to it, you've effectively concentrated 1000 people worth of SP into ONE paid vote. That means 1000 people who cannot support your work, as they are being paid to look away. If the concentration of wealth is for profit or not for profit, doesn't matter, the negative effects of concentrating SP into fewer hands still exist.