This doesn't demystify SEO. There are just so many factors involved in SEO, and unknown factors. Something that works today may not work tomorrow. The only true guideline to go by is to create great content for humans, period.
I agree with you about the great content for humans bit, but that doesn't mean that you shouldn't still aim to maximize your current traffic through technical means.
If it gives you a whitehat traffic increase of even a few percentage points, that can still mean a big deal, hundreds if not millions of dollars.
Here's the crazy thing about SEO - specifically SEO in relation to Google. This is a gut feeling based on over 10 years of building sites primarily with organic traffic:
I don't think you should try to do "best practices" with SEO. Over the past couple of years, I feel like Google is penalizing sites that try to dot all the i's and cross all the t's. And why shouldn't they? White hat SEO is still gaming the system in a way. In google's eyes, the pages that contain the very best content for humans should show up higher in search, despite them not being optimized for SEO.
I've been seeing more success with pages that are not optimized, pages for which I didn't pay any attention to SEO. The content on those pages are geared for humans and contain great info, that's it. I don't pay attention to URL, title tags, meta tags, etc. Google is getting very good at filtering this out, not sure if they have a team of humans that are whitelisting sites now, but I've given up on trying to optimize for SEO and it's worked wonders.
