When should soft multitenancy be used over hard multitenancy?

Soft multitenancy(Namespaces, RBAC, Network Policies) → assumes some level of trust between tenants, focuses onresource sharing and efficiency.

Hard multitenancy(separate clusters or strong virtualization) → strict isolation, used when tenants are untrusted.

Exact extract (CNCF TAG Security Multi-Tenancy Whitepaper):

“Soft multi-tenancy refers to multiple workloads running in the same cluster with some trust assumptions. It provides resource sharing and operational efficiency. Hard multi-tenancy requires stronger isolation guarantees, typically separate clusters.”