Perhaps if you learned to read, you'd be able to comprehend the difference between "following the development of the Linux kernel" and "loose coupling". Let me help you.

"Following the development of the Linux kernel" means that the glibc and userland people continually track changes in the Linux kernel and fix bugs or implement new features as necessary.

"loose coupling" means that Linux-related development on these tools does not cause the functionality of these tools on non-Linux platforms to be affected. Another way to put that is that the functionality of said tools does not depend on Linux, even if Linux is the target that gets the most attention these days.