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.
Improving your content to optimise for SEO is not the same as improving it for the user. I hope that fact was made bloody obvious by SEO-hugging websites full of garbage occupying top spot of many google searches.
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!
There is absolutley a blend that the smartest marketers understand how to activate. In fact, id argue that the advent of adding 'reddit' to the end of a query signals a change is necessary in order to really surface the best content for a given result. Even Quora is filled with spam these days. Spammers will get into anything wherever they can.
With that being said, in any marketing tactic, the right way isn't always the best way - however - understanding why some garbage site ranks for your query is incredibly helpful in figuring out how you can improve your content to do the same.
This seems a bit backwards to me. If you have the best website for a subject, and Google doesn't rank it, the problem is not that your SEO is bad, it's that Google is failing. You have the best website for the query and Google's job is to find the best websites for a query. If Google fails to do that, that shouldn't mean you need to do more work. It should mean Google needs to make some kind of change.
