Why does Mutating Webhook require both parent-resource and sub-resource?

This is related to Dynamic Admission Control.

Mutating the status subresource in mutating admission webhook requires both parent resource and subresource, for eg - Node and Node/status present in the webhook i.e.:

- apiGroups:
  - ""
  - v1
  - nodes
  - nodes/status

If I try to specify just nodes in the webhook, the status is not updated (status can be updated for node, see Advertise Extended Resources for a Node). Whereas if I include both resource and the subresource, the mutation is successful.

I was able to find:

regarding this but, it too does not mention the reason for doing so.

What is the reason to add both parent resource and subresource for modifying the status subresource?