Um, your question is unclear so I'm not sure exactly what answer you're looking for but, in short, yes, there's quite a lot you can do to improve your site from an SEO perspective.
Let me try to rephrase. If an SEO comes and regurgitates the same tools and strategies that are easily obtainable to me, what value is the SEO adding? Are there limitless things outside of a predetermined checklist of 50 or so items that fall outside my general responsibilities as a startup founder? Which would therefore require me to outsource it? If an SEO told me that you could go build link farms and that would boost my SERP, I'd pay an SEO. Seems like a good ROI right?
My general assumption with SEO is (1) create good content and (2) make sure content is tagged correctly (3) share content.
Honestly, I'd love to be sold on why I should ever spend money on it, but given the recent updates to the Google algorithm, I can't seem to figure out why...
The most difficult part of SEO (and, perhaps tellingly, the part covered only extremely briefly and superficially in the PDF) is getting links from relevant, high-authority sources with relevant anchor text. It's more important than any other factor by a vast margin. Building image sitemaps or optimizing your custom 404 error pages pales in significance by many orders of magnitude. On-site SEO is child's play compared to offsite SEO.
Getting these links ethically is a hard problem to solve, even for a high quality site with unique content.
I don't have much connection with the world of commercial SEO, but I imagine there are people good enough at solving this problem to charge a premium and get good returns for their clients.
So you're basically saying your knowledge of SEO was limited to crude link building tactics that have since been rendered ineffective by algorithmic updates. You're not alone, as that certainly cuts out a large swathe of what SEO was.
That's not to say there's nothing left though. And although there's much debate on whether what is left is actually 'SEO', good old fashioned PR, or now falls under the related, but rather nondescript 'content marketing', the business case for conducting such activity is still very strong in many cases.
My general assumption with SEO is (1) create good content and (2) make sure content is tagged correctly (3) share content.
Honestly, I'd love to be sold on why I should ever spend money on it, but given the recent updates to the Google algorithm, I can't seem to figure out why...