This may be hard for site owners to hear, but Google doesn't really care about your websites success. What they care about, just like every other online business owner, is their target audience. You might be in the business of selling enterprise software, dog grooming services, or small business financial consulting---Google sells the organization of information.
Part of the reason Google has the search market share it does is because for a very long time they provided the best search results possible and people want to use a product that produces great results. Would you go to a dog groomer that messed up your poodles cut every time? Would you hire a financial consultant that gave you terrible advice? Of course not! Just like every other business owner out to provide the best product possible, Google wants to make sure the SERPs give users what they want so they will come back to Google time and time again.
Then Why Bother With SEO?
I can see the wheels spinning now; if Google doesn't care about your websites success than why should you bother with SEO?
The simple answer is that good SEO helps Google produce better search results. They want you to do a good job with your SEO so their product improves. After all, it doesn't help Google if spammers are outranking legitimate sites any more than it helps you.
Searchers don't want spam, they want information. Your SEO efforts help Google provide the results searchers are looking for. And in return your website benefits from an increase in traffic, online brand presence, and ultimately with more business.
Google may not necessarily care if your online business succeeds, but they do want your site to have the best SEO possible, which is why they provide site owners with as many resources as they do.
Then Why Doesn't Google Tell Me How It Works?
In a perfect world Google would lay all the cards on the table and tell site owners exactly what they needed to do to rank well in the SERPs. And since they don't many site owners feel like Google is simply playing games with their livelihood, holding back crucial pieces of information that could make all the difference.
But you have to remember that there are thousands, maybe even millions, of spammers out there that are looking to exploit the loopholes in the Google algorithm. If Google lay out a step-by-step guide for site owners, then spammers would use it to their advantage and completely undermine the search results.
As John E. Lincoln said in an interview I did with him,
Google is not transparent with their algorithm and I don't blame them. Their goal is to provide users with the most relevant natural results possible. SEOs by nature are trying to manipulate the results in algorithms which can put them in conflict with Google's goals. With good reason Google does not want SEOs gaming the system. Google has always been guarded and cryptic about the information it makes public concerning its algorithm. In the past, too often SEOs were able to exploit holes in Google's algorithm through suspect techniques to the detriment of the good guys trying to do it the right way. Perhaps Google has at times been over-zealous in attempting to close those loop holes, but it does seem the more recent updates have really done a better job at rewarding the good and punishing the wicked.
Many site owners that were hit by the Google Penguin update feel like they were unfairly penalized, but in my experience I have not yet come across a site that was playing 100% by the rules and was penalized. Whether they meant to or not (and many did not) something in their SEO past worked against them when Penguin was rolled out. Google was not out to get honest site owners but many of those sites that fell on the wrong side of the algorithm update are still fighting their way back.
I Didn't Know I Did It Wrong!
Its hard to see site owners that didn't realize they were doing anything wrong be penalized but that's why its so important that DIY SEO site owners take the time to educate themselves as much as possible and rely on industry leading sites and blogs for information.
There are hundreds if not thousands of SEO blogs out there and many offer contradictory advice, but if you stick with the Google and Bing Webmaster Guidelines and those high-profile SEO blog like Search Engine Land you'll be sure you're getting the right kind of guidance.
Remember, Google isn't out to get you or your website! They want you to succeed in your SEO so it helps them clean up the SERPs. The algorithm may not be perfect but it is constantly being tweaked and updated and as John E. Lincoln pointed out it is getting better and better and rewarding the good.