Whether a country's citizens well being should be directly linked with the efficacy of the leader is a moot question. There are many countries in the world where it is crystal clear that the citizens are not living well just because the leaders are not effective in maintaining good relations with other countries or because these leaders don't have the required knowledge that is required to run a nation which makes them quite ineffective. While, in general, the efficacy of the leaders has an impact on its citizens, it is also the case that there are many other countries where the citizens of the country believe that their leaders are effective but still there are a lot of people who are living in a penurious state in those countries.
In countries like North Korea, where dictatorship is the form of government, most of the people are indigent. They don't have enough food to eat. Their children are dying of starvation and the only thing responsible for this is the ineffectiveness of its leaders. The supreme leader of North Korea doesn't have good relations with most of the countries. Instead of providing food to the people of the country, he is focussing more on the military arsenal and wants to prove to the world that his nation is an exemplar of a perfect nation. Because of this most of the countries don't have good relations with North Korea and have imposed sanctions. Thus, due to the ineffectiveness of the leader of North Korea, the citizens of North Korea are living in a pitiful state.
On the other hand, there are some countries, where the leaders of the country are believed to be effective but there is a mix of both classes of people: those who are living luxurious lives and those who are living below the poverty line. For instance, in India, there are a lot of people who think that the current leader is a very effective leader. He has maintained good relations with other countries. He is focussing on Foreign Direct Investment to help the citizens of the country and provide them with jobs so that they can provide for themselves and their families. Still, there are more people in India, who go to sleep without a meal than the number of people who are benefitting from these policies.
While the essay propounds that leaders effectiveness is linked to the well being of the citizens in some sense but not completely, some might argue that if the leader is so effective, then he should be able to take care of all the people of the country by making policies that benefit all of them. But, there is no silver bullet that can resolve all the issues of a country's citizens. Even if an effective leader makes policies that help a cohort of the nation, it is highly likely that it may not be beneficial to a niche of the nation. For instance, the introduction of GST in India helped a lot of middle class and upper-class businessmen of the country, the lower class and SMEs were burdened because now they had to hire CAs to help them file taxes.
Does the efficacy of a leader directly impact the well being of the citizens? The answer in some sense is yes. Ineffectiveness of a leader can be seen in some countries where the citizens are living in an indigent state. However, there are some countries where the leaders are effective and they try to help the people of the country, there are still lots of people who are living poorly.