For the regular folks who want to use the Internet, let me put it this way:
Okay, I’m calling it: if you’ve ever advocated, used, bought, or benefitted from guest blogging, you're part of the problem on the Internet. It has always been and will always be a scummy and spammy SEO technique that devalues and dilutes the value of information on the Internet. It is pure entropy.
And no, I'm not talking about Charlie Stross taking a vacation and having relevant people write on his blog for his fans. I'm talking about the brokers, the people who buy and sell content and links, the people who see their online content as a means (way to make money by selling ads), not an end (way to give value or entertainment to people).