Page ranking is extremely critical for all kinds of websites. So, there's all kinds of reasons for people to cheat the system. And, when cheaters get caught,

Page ranking is extremely critical for all kinds of websites. So, there's all kinds of reasons for people to cheat the system. And, when cheaters get caught, they get the appropriate page rank penalty. Saying 'but this other site paid for backlinks with money, we only paid with tweets' isn't really an appropriate defense.