It's good for isolation: i.e. in general if you copy a directory containing an NPM project to another location, in general it will just work, and deleting somet

It's good for isolation: i.e. in general if you copy a directory containing an NPM project to another location, in general it will just work, and deleting something elsewhere on the file system should never affect the project. In general I would argue this is a more important property for dependency managers to have rather than using the least amount of space possible. If you really want to avoid it you can install everything as a global dependency, but it's not best practice.