You have to remember that Google is based on the model of academic citations. In the web-based world, citations equate to links. From what I've seen, Income School preaches that if you build it they'll come. Or that if you create good content, it'll earn links and get traffic. I think that is pretty good advice (certainly, high quality content is better than low quality content), except it doesn't take into account that the world is commercial and that despite all intentions from Google to have a level playing field, money makes the world go round. You might have the best content ever, but if you don't have any links to it, your competitor's content that has 10 outreached guest posts linking to it is likely to rank higher, get more traffic and as a result, acquire more organic links. That's a bit of a divergent rant - sorry. But what I wanted to say in response to your post is that E-A-T is based on factors that can be quantified. Google is an algorithm. Expertise, authority and trust are all subjective. To make the subjective into the objective requires weighting criteria that can be clearly measured. Google is based on links. Its not looking at the qualifications of the writer in the bio to a blog post because it doesn't know whether a degree in astrophysics actually means that the writer is qualified to write about particle physics. Its looking at whether sites it already trusts on that subject (i.e. that are about the same thing and that themselves are linked to) cite (link to) your webpage. To overcome E-A-T issues, you don't need to change your author bio or add an about us page. You need to acquire links from topically relevant and preferably highly cited (linked to) websites. And the problem then with the Income School approach is that if you're not actively seeking links, the rate at which your site acquires them is going to be much less than the rate at which someone who paying for outreach is acquiring them. Your website will be relegated in the SERPs, which means less eyeballs on your page, which means fewer organic links. The utopia of just being able to focus on high quality content is a wonderful ideal, buts its fantasy land. To be successful, you either need to be operating in an area with no competition, or you need to be greasing the machine with large wads of dollars faster than your competitors are doing it.