It replicates the API and provides a distinctly primitive implementation of that API. By contrast java streams provides an API that can never, ever be implement

It replicates the API and provides a distinctly primitive implementation of that API. By contrast java streams provides an API that can never, ever be implemented in such a way as to issue a clever SQL select. I don't know whether the JINQ people plan to write a good query generator. But if I were the maintainer, my plan would definitely be to focus on the API first and only then work on optimal backend implementation(s).