I think the point is that search-engine optimisation itself is a farce, perpetuated by confidence tricksters—some “SEO experts” do not know that they are conning people, charging people for useless reports, yesterday’s advice and for services that clients could just as easily handle themselves.
Obviously no offence should be intended towards victims of SEO cons, but the fact is that it’s a con, and that’s probably why it seems confusing to people without technical knowledge. I have been a web developer for nearly a decade and I still struggle to understand what value an SEO expert/agency is supposed to add.
Anyone honest in the field will say that if your website loads reasonably quickly, works on mobile phones and desktop, and comprises useful, quality, regularly-added content—pertinent to things that people actually search for—your website is more or less optimised for search and the rest requires time for search engines to crawl your website and for people to search for it, talk about it, etc.
This is the sort of thing that necessitates a good web developer/team and a good writer, and maybe someone to manage social media and press and stuff like that. You don’t need to pay money for some “SEO experts” to give you outdated advice and charge you monthly to provide automatically generated reports from services you could use yourself, for less money, and which provide almost pointless “ranking” measurements.
SEO activities of any value include reaching out to high-traffic, trustworthy websites to feature your site (this is PR) and to log into Google Webmaster Tools/Search Console to disavow any “spammy” links to your site (this is something anyone could do).