The Linux kernel would maintain a list of the latest Intel microcode versions for each CPU family, which is based on the data from the Intel microcode GitHub repository. In turn this list would need to be kept updated with new Linux kernel releases and as Intel pushes out new CPU microcode files.
Sounds like that would be outdated for everyone without a rolling distro.
Sounds like a user space application, there's no place for this in the kernel. So would you need to upgrade kennel and reboot to update the list? Nonsense.