> There's at least a dozen languages you could have chosen, and that others have chosen for any given use case. within some bounds, it makes very little difference.

It's about quality of life and picking the right tool for the job. There are some problems I can solve in Haskell, that I simply could not solve in Java, it would be too hard and too much work. Java is a simple language and therefore it's much easier to reason about the performance and space usage. There are thus many problems where Java would be a better fit.