Earlier quoted context omitted.
>If you're seeing lower traffic on your site and don't feel like you need to improve the content or do something different, you deserve to be losing that traffic to someone else who does. I disagree. Suppose you're unquestionably the world expert in some niche field, and you write a site with high-quality, timeless content. It would be really infuriating if some SEO knocked you out of the search results with an adfar…
You're missing the point here. Regardless of the causes of the decline, there are invariably things you can do to improve your content or just generally change your approach.
In fact i might google a spesific product, like a Monitor, and the top result will be "but Monitor XYZ on Amazon". When i click on the link, turns out they don't actually sell or stock that product at all!