What about standardisation that comes with using a framework like kubernetes , while not using k8s you end up with adhoc deployment methods, clunky work arounds of handling networking, policies, secrets etc, with Kubernetes or even ECS it signals that the team or the developer is looking to use fixed set of rules for infrastructure, also k8s scales well even for smaller apps
Seriously, I use k8s for the same reason I use docker: it's a standard language for deployment. Yeah I could do the same stuff manually for a small project.. but why?