Google search engine considers back links factors in top ranking results also. Also it depends many factors like quality & informative content, proper optimize keywords on webpage, links and other factors of on page optimization.
There are also black hat techniques like web spam,cloaking,keyword density, spamming back links, low quality content, copied content and more. so you think which steps you want to use for stop SEO services.
First, I don't quite understand the second question that you've posed through your thread. Google is not against webmaster using proper SEO techniques to rank their sites, the problem is with using black hat SEO tactics. That's the main reason Google is constantly releasing updates in order to crack down those who are engaging in this type of practices.