It's not. At Ksplice we had a build farm and whenever a supported distro would release a new kernel, we would generate new .ko files for that kernel, usually within 24 hours. It was a lot of work, and very much specific to the Ksplice product. These days, between docker and DKMS, and limiting yourself to supporting a specific device, you'd have a much easier time of building a build farm to release a compiled .ko, if you were a hardware manufacturer that wanted to support that.