"I have great content" - is there a more meaningless claim on the subject of SEO?
It is meaningless in the rhetorical sense that no one thinks the opposite is true. I have yet to see someone claim they have average content. As a matter of fact (though depending on your selected meaning of the word "average"), half the sites on a given topic are below average- anyone want to self-report?
But it is also meaningless in a more substantive sense. What do we mean by greatness? How do we measure it? In what sense can this be true?
Can greatness be measured statistically? Is bounce rate, time on site, or returning traffic a basis for determination?
Is greatness related to the veracity of the content? Can you have a "great" article if the central claim is false? For example, could an article on the [Brilliance¦Disaster] of [Trump¦Brexit¦Merkel¦AfD*¦Macron¦Maréchal] (delete as most easily offends you) that is "great" if you believe the opposite? Can you have a "great" article on unicorns?
How does the concept of "greatness" intersect with other criteria, such as target audience. My "great" primer on, say, GDPR would be less than helpful for a first year law student. The law student's dissertation on the same subject would be a useless guide for webmasters.
How do you assess "Greatness" in your own output?
How do you assess claims of Greatness made by others?
*For those that care, AfD is lead by Gauland, Meuthen and/or Weidel. No, me either.