I agree that many so-called experts are guessing and spread misinformation, but Google certainly does say what we need to know. Google doesn't reveal its algorithms and exact methods, but they constantly provide good advice for webmasters and business owners. If you pay attention to what Google says about search rankings and content you will do well. If you pay close attention to how Google responds to various situations, you will do even better. You only really run into problems when using tricks to fool Google or violating the Big G's terms of service.
I somewhat agree with you and especially the part about listening only to Google as there are many many people who tell you the secrets of Google but the truth is that even most Google employees only understand their part of the enterprise and are carefully shielded as to the nature of the algo, not even close to the specifics I agree that Google is mostly honest with their advices and if you behave the same way, everything should be ok but that is often not the case it boils down to using maths to understand people - the principles of economics - and that has proved that 87% of people are honest, not 100% as it must be to rely on an algo to comprehend their nature