This might seem like a ridiculous question to many, but apparantly nobodies ever written about it (per a tweet from @DuaneForrester a moment ago on twitter.
So: why is it important?
Content is one of the three pillars of search – no website can compete in even reasonably difficult serps without having a fair grasp on all three of them.
Content. Technical SEO. Authority (links).
That’s it, those are the three things you need. Without a reasonable baseline of technical SEO, search engines can’t spider your site and ingest the content. Without content on the site there would be nothing to rank. Without authority (yes, links) you can’t rank for anything competitive.
SEO is genuinely that simple. It’s the massive amount of nuance in each of them that is key to developing your site, or even your career in search.
In order to “master” SEO (that’s in quotation marks, because as a field that’s constantly evolving, it’s literally impossible to fully master) you need to have a solid understanding of the three, but for most people – and I include myself in this – specializing in one of the three is the best way forward.
Each of them have different requirements on us, and suit different people. You’ll find a million tweets or blog posts about how A is more important than B, but the reality is, they all work in tandem. Together.
So to sum up, without Content, Tech SEO is irrelevant, as are links. But you can say the same about the other two as well.