But the Linux kernel was central to the advent of FOSS operating systems. If it were up to the GNU project we’d still not have a working OS. It’s unfair to speculate because maybe the BSD family would have taken over but it’s worth mentioning that Stallman also passed up on the BSD kernel as well. So, really, the GNU userland had to be dragged into widespread success against its goals.
Also, it’s a lot easier to replicate a basic userland than it is to get a working OS going. I think Linux would have done well even without the GNU utils but the opposite is demonstrably not true.