What is an Ethernet driver but CRUD against a DMA ring?

A heap of sand minus one grain is still a heap, but eventually it's a DMA ring.

To use wikipedia's definition of CRUD, "[CRUD] are the four basic operations of persistent storage." etcd is persistent but a DMA ring is not?

But fundamentally the main way k8s resources are implemented is by observing the current state and desired state and updating the current state to be closer to the desired state, sometimes performing other actions (which are often updates on a different resource's setting)... so whether "other actions" are enough to make it not-CRUD is to the eye of the beholder.