It is true that a lot of those use cases are covered by "basic" Kubernetes (or Nomad) without the addition of Istio or similar, e.g. service discovery, load-balancing, circuit-breaking, autoscaling, blue-green, isolation, health checking...
Adding a service mesh onto Kubernetes seems to bring a lot of complexity for a few benefits (80% of the effort for the last 20% sort of deal).
> Adding a service mesh onto Kubernetes seems to bring a lot of complexity for a few benefits
I think the benefits are magnified in larger organizations or where operators and devs are not the same people. And the complexity is relative to which solution you pick. If you're already on Kubernetes, linkerd2 is relatively easy to install and manage; is that worth it? To me it has been in the past.
Adding a service mesh onto Kubernetes seems to bring a lot of complexity for a few benefits (80% of the effort for the last 20% sort of deal).