That's true to some extent, but I think the real reason for the coupling is because that's just IBM's use-case and worldview. Cockpit is essentialy a wrapper over systemd commands, and one commentor has demonstrated how it could have been envisioned as a modular platform allowing end-users to wrap anything from direct kernel interfaces to entirely custom commands. They've made something useful and beautiful, but I wish it had been designed to make less assumption about it's runtime environment and expose it's toolkit to end-users so that we could all enjoy it for our own needs.