"pay for pr"?

Great article on Paying for Pagerank:
http://www.webpronews.com/ebusiness/sma ... bsite.html

perhaps this isn't a question that can't be answered, but:

why does google "kill" the PR of a page that sells pagerank? when you think about it, ALL advertising is "selling pagerank" even if indirectly.

seems pretty arbitrary to me.

there have been sites that google does not allow the PR to pass onto links:
http://www.blockedpr.com/

Because you are not suppose to sell or buy pagerank. Google hates artificial Pagerank. I agree though, its all advertising.

what if you sell adblock? Google sells sponsored links that passing PR.