Not necessarily... I maintain servers which offer ssh access to researcher to run long running computation. They perform their computation anyway they want (using interactive tools under screen, by running their own code, etc.), and there is no way I can checkpoint their computation, so I cannot reboot the system without killing their computation, which is precisely what I am supposed to prevent. Planned power outage and the like can be handled through suspend-to-disk, but updating the kernel require a reboot.
Since we provide ssh access to a number of users, local privilege escalations are a problem, but I cannot just reboot the system whenever I want.
Of course I would need a high level of trust in ksplice before using it.