I think it's easier to run a small k8s cluster than it is to attempt to recreate a lot of the functionality provided manually, especially if you're running in a cloud where the control plane is handled for you.

It provides unified secrets management, automatic service discovery and traffic routing, controllable deployments, resource quotas, incredibly easy monitoring (with something like a prometheus operator).

Being able to have your entire prod environment defined in declarative yml is just so much better than running something like a mishmash of ansible playbooks.

If your application runs on a single host and you don't really care about SLAs or zero downtime deploys, sure, use some adhoc deploy scripts or docker compose. Any more than that, and I think k8s pays for itself.