Why Google Page rank Drop Down?

On November 1 (Thursday) very popular websites, including Washington Post, TechCrunch, etc. saw that their Page Rank Drops according to Google. The Google Page Rank is a number scaled from 1-10 that essentially ranks a website importance in the Google Search Engines. But, if you have been following SEO over the years and Google Page Rank you probably already know that the Page Rank system is becoming less and less important. During this recent Page Rank drop, the big sites who saw their rank plummit proved this fact in that their rank did drop, while their traffic stayed the same.

Why Did Google Drop Page Ranks?

Google said that the drop in page ranks was a direct result of websites who use paid linking systems and back links in order to get a better Page Rank effectively getting better search results. Google has adamantly resisted the paid linking system and says that it is unethical according to the search engine's ranking and result system.

On the Other Side...

What if sponsors pay for links, but the links are similar to your website and act as any other advertisement would.
Are we not supposed to put advertisements on our website?
Only Google is allowed to earn a profit from the entire internet?

Brendon Sinclair from SitePoint said it best

"But the fact that Google took action on these sites shouldn't come as a great shock to anyone. The point is this: if your site relies totally on Google for revenue, you're nuts. Google isn't here to help you. What comes first for it is making as much profit as possible"