Yikes! You must have had some bad experiences with SEO's, sorry to hear that.
Just the experience of actually understanding HTML, CSS, accessibility guidelines like the WCAG, how HTTP works, how caching works, and a general understanding of how search engines actually work -- mated to actually bothering to listen to Matt Cutts when he says things AND watching so many people being led down the garden path to failure by those who don't.
SEO is a very small and semi-important part of site-building, and in terms of on-page "SEO" should be a natural part of building a website requiring no real expertise if you have ANY business writing about the topic of the site, and ANY business marking the content up with HTML. Off site promotion to generate back-links isn't rocket science if you bother learning to use social media sites, and have content of value people actually want, and will therein be linking back to organically.
ANYTHING more than that is 100% grade A farm fresh BULL... and that is why there is NO legitimate reason for there to be ANYONE calling themselves an "SEO Expert" when that's "all they do is SEO". More so, it's why the mere notion of companies where SEO is "all they do" is such idiotic halfwit nonsense it can only be considered nube predation.
IHMO most all SEO "experts" are nothing more than sleazy scam artists preying on the ignorance, naiveté and innocence of others -- even sadder many of them seem to believe their own BS so they're unaware of just how much bekaptah nonsense they're spewing.