The Istio project is not supposed to be tied to Kubernetes. It is supposed to be a general-purpose service mesh.

That being said, I have been looking for a while and I can't find anyone who uses it in production on a platform other than Kubernetes.

Also worth noting that Istio is not part of the CNCF while Linkerd is.

It is a good note to make. How does this bear weight on the question above?

He was asking why Istio was not included as part of Kubernetes itself despite both projects originating at Google. I was implying that there must be some reason as Istio is not in the CNCF while Linkerd (arguably an Istio competitor) and Kubernetes are. To further that idea, it seems that Google wants to maintain direct control over Istio itself, rather than put it into an organization with multiple sources of institutional governance (Amazon, Huawei, Samsung, Microsoft, Oracle, etc.). If Istio or any other service mesh had been incorporated directly into Kubernetes by Google, they would have lost some control over it.

(There are also obvious technical reasons for decoupling something like this from Kubernetes, mostly the opinionated nature of forcing a service mesh over other potential solutions).

So kubernetes seems to be one of Googles biggest efforts at really building a healthy open source project for Borg v2. Perhaps they wanted it to be mostly community driven? It’s for this reason that they collaborated with others to introduce ISTIO so the community doesn’t feel like Google is taking over or whatever fears a lot of OSS folks have of the company.

Google's a big place.