Why Google Won’t Reveal Secret Ranking Factors, But Gives Plenty of SEO Advice

Google’s goal as a search engine is to provide users with the most relevant results for their queries and the best user experience. For this reason, Google keeps its 200+ ranking factors a secret. While some of them are well-known, others are not, and how much weight each is given is perhaps the biggest mystery.
Google doesn’t want people to be able to game its system because this will have a negative impact on search results, and make the user experience poor. This is nothing new. Danny Sullivan recently asked Google CEO Eric Schmidt why they couldn’t at least list the factors, while keeping their weights secret. Schimidt basically said that this would be revealing business secrets. Fair enough.
While one may understand why Google goes out of its way to keep this information under wraps, some may wonder why they go to the trouble of providing webmasters with SEO advice, tools, and resources. After all, Google is going to deliver the results as it sees fit right? This is the topic of a question someone sent into Google’s Matt Cutts who has provided a video with his response.
The question is really coming from the angle that Google should rather not have people optimizing their sites, so they have to buy ads to gain visibility (more money for Google). Of course while Google may want you to buy ads,  this is not the company’s approach. 
"Whenever the web does well, Google does well," says Cutts. 
"I don’t think that it has to be something like, ‘Oh, we help websites rank better and they don’t need to advertise,’" he says. "That’s sort of a short-sighted view. We say, ‘Look, we try to help people make the web a better experience, more people will be on the web, they’ll stay on the web longer, they’ll be happier, and…just the halo effect – the reflected effect of all of that is that people will search more, and then a few of the times they’ll click on the ads’".