Google's revenue depends on providing the best results it can to searchers, within limits of result pollution they do themselves (clearly demarked advertising at present). If they allow cynical SEO then the results get worse for everyone and people will look for alternatives.

I'm glad they have a proactive slap-down policy. Let's not go back to the late 90s and the likes of altavista, when you might have got one hit in ten pages of spam, SEO link farms.