This is a great example of an edge case which many people might never need but is really useful in a pinch: that’s what provides the equivalent of the Mac target disk mode, which is really handy if you need to repair a no longer-bootable system.
Where would you put it instead of something started by pid 1? It needs to boot the kernel and unlike macOS they have to run on a ton of different architectures so they can’t count on the firmware.
Kitchen sinks are generally useful, but 17 kitchen sinks in a helicopter is not a good idea.