More importantly, projects like this frequently spread their ideas elsewhere, even if the project itself isn't very useful. Another possibility is that someone gets a bunch of skills from developing in the much more open territory of Hurd and uses that knowledge to contribute in a more limited fashion in the Linux kernel.

Of course, I'm sure that Richard Stallman & Friends would be unhappy with my characterization of Hurd as an academic toy project, but them's the breaks. It's on them to show that this is dompetitive on any level with Linux, and right now that's not the case.