[shirakawasuna]

Consider that summarizing it as a single quantity is already unwarranted and somewhat arbitrary. The question should be about the utility. What is the utility of having one major number that is supposedly quantitative and consistent rather than, say, five metrics related to material status? The latter will provide more opportunity to compare "like to like", after all, and there's no reason that the universe must conform to a single metric being in any way valid. This is made even worse by pinning it to a (controlled) dollar value rather than some aggregate quantity of material well-being.

For example, according to this metric, the vast majority of poverty reduction happened in China. What factors can we attribute to that development? Well even asking that question means we have to go back and look at other metrics and means by which to understand economic systems and the distribution of material goods. The moment we ask a pretty basic, but arguably more relevant and useful question, we have to throw this metric away and do something else.

And when I've encountered this information in this past, the utility seems to be more about propaganda and lazy inferences than anything else, and often among famous academics. While we all have our bubbles, it does make you question the point of trying to make poverty just one quantity.