Often, people compare different countries and argue about which is the best nation. Even though there is no widely accepted parameter for comapring two nation's greatness, the promt claims that the best way to do so is to look at the accomplishments of a nation's rulers, artists or scientists. However, I am afraid I mostly disagree with this position for two main reasons, which I will elucidate below, but I do concede that, if not complete, these people's achievements can represent a good picture of the nation.
To begin with, there is no specific parameter or a hard and fast rule to compare achievements of two different people in same or different fields. For example, one cannot say that Newton's classical mechanics is greater than Darwin's theory of evolution. How will you compare achievements of Donald Trump and Narendra Modi? Even if, one manages to compare or evalute someone's accomplishments, it necessarily doesn't indicate the nation's greatness. For example, under Xi Jinping's rule China reached new heights and broke all previous records of China's GDP, and became world's manufacturing hub. Xi Jinping himself is a billionaire and has achieved many professional and personal accomplishments, and still many might question China's greatness due to lack of free will, lack of democracy and treatment of Uighur Muslims in the country. Similarly, what does the fact that Donal Trump is a billionaire has to do with America's greatness? On a similar note, discovery of a new atomic phenomenon by a scientist of a country does not mean people of that country are happy, or that the nation is great. Hence, achievement of rulers, scientists, or artists cannot be regarded as sure shot indicators of a nation's greatness.
Moreover, the claim completely fails to acknowledge this fact that there might be other equally good, if not better, parameters of comparing nations. The definiton of greatness itself is very subjective and a great topic of debate. Greatness can have different meanings for different people. For some, greatness of a country might be indicated by it's military power, or some might think that a nation is great if people of that nation are happy, or some people may relate greatness with wealth or GDP per capita of the country. Additionally, people can be biased towards or against a country while evaluating its greatness. Being an Indian, I might give more weightage to Indian accomplisments. In short, a country can't be evaluated greater overall based on some factors or accomplishments, but we surely can compare two countries in a more specific field (say safest country, country with hifghtest GDP per capita, freedom of speech and media etc.)
However, I do feel some achievements might indicate that a country is doing great. For example, scientists' research in the field of green energy might indicate better and easier shift of the country to a sustainable power source. Achievements of artists may indicate free will, and passion to pursue dreams among people of a country. A good ruler may ensure a bright future and development of the nation and vice versa.
In conclusion, the author's claim might be true to some extent but I mostly cannot entirely agree with the claim.