GDP is a useful metric when we remember what it problems it was created to solve --e.g. in the Great Depression there was a concern of a decline of economic activity and a way to measure such activity and decide whether it was at a depressed level, and to what degree.

Similarly, the reason in international finance there is a focus on current value GDP is because lenders want to know whether a nation can repay foreign loans. As foreign loans are measured in dollars, lenders care about GDP in dollar terms.

But as is often the case, when people with money or institutional power create a metric for their own use case, many other groups see that and go "Aha! Free data!" and they start writing publications using this data for their own purposes, often forgetting what GDP is actually measuring and forcing it into a proxy for what they care about, for example, development economics, and often this is a poor proxy.