Does Guix use the Linux kernel or Hurd? In any case, I can understand kernel growth. There are a lot of new drivers, new and old architectures (386 machines were supported in Linux until a few years back; and there's still a fork that does), all the new file systems, all the new networking and cgroup isolation. You can build a minimal kernel without a lot of that stuff, and it will still run on older embedded hardware. But just having a large kernel source and large default kernels/initrds isn't bloat so much as supporting a lot of hardware possibilities.