To me the core of k8s is pod scheduling on nodes, networking ingress (e.g. nodeport service), networking between pods (everything addressable directly), and colocated containers inside pods.
Declarative reconciliation is (very) nice but not irreplaceable (and actually not mandatory, e.g. kubectl run xyz)
Declarative reconciliation is (very) nice but not irreplaceable (and actually not mandatory, e.g. kubectl run xyz)