This is good insight. There's one additional thing I might add. I think there was an ownership issue at stake as well, the FSF always has felt like they should own the full OS. This implies that GNU is missing a kernel. But, as you state eloquently, Linux filled the gap without pretense.

It attracted people to the project, just because it was fun and wasn't trying to initially displace anything in particular. I find it interesting that the FSF still wants to own the entire stack, given the movement that they started with the GPL.

GNU got a kernel, it's Linux.