Isn't eselect for cases where I might want to reconfigure something or add configuration values such as for bash-completion, do testing with java-vm or python implementations during development, switch opengl implementation depending on the graphics driver loaded and whatnot.
I don't see any of this applying to init system, nor do I see a reason to randomly switch between those. It's rather something to configure during installation, so I'd rather expect proper documentation. But I am not opposing, I just find it weird.