Have you heard about Yandex? it's a search engine which is more popular then Google in Russia (really, check Alexa for russian sites) and they are in war with sape and other link-selling platforms for years now but they can't win here because backlinks is fundamental part of the ranking and they can't just ignore them, nor they can make bots that can judge if this current backlink is from SAPE or natural one, they neither can just penalize all those sites in SAPE because there are 600,000 sites and most of them are hacked sites, I've seen dozens of some serious companies sites and even some university sites (not just .edu sites but real sites of serious universities), if they ban and ignore backlinks comming from those sites there will be chaos in SEO!
Here is another thing, Google actually needs IMers to work on SEO because, let's be honest, when someone spends 200$ on those sape links, we will most likely have awesome on-site SEO with really nice posts and stuff - I mean really good quality website and that's what Google wants! But they of course can't say to us that "Hey! We love you SEO guys here is how our algorithm works and use this to rank whatever you want and put adsense on it", they are making updates not because they don't like SEOers but because we have doubts about how their algorithm works and try to manipulate that and actually rank junk, so they have to change algorithm so that we will start from scratch and build quality sites to rank, then we will again find roughly of course how algorithm works and start ranking shit and they will again change it and so will be always..
