The GKE reference is a lot more relevant than you think, it's just a bit deeper below the surface.
Google's relationship with k8s and GKE and in particular their motivation for creating an open-source orchestration service is well documented and frequently retold, but ironically appears to not be well-understood.
With any sufficiently complex compute solution, you're going to need both a platform and some sort of management. Typically vendors sell you their management service (for which you often pay a recurring fee) by locking you into a proprietary platform. What's more, the management service can be dismal but you'll pay anyway because your app is built on their platform. It happens everywhere, the industry is full of examples, and anyone could see that it was going to hit Cloud sooner rather than later. And the result would be ... bad ... for everyone (customers and providers alike) but the dominant platform.
So Google took an exceptionally gutsy gamble. Google excels at platform management. They invented SRE. They posited that in a level playing field, all else being equal, Google would have the best platform management service, and people would pay for it based on its merits alone.
By making k8s open source, they leveled the playing field. It was by far the best tool for the job, and everybody could have it at no cost; neither money nor burden. So there was no business model or justification for building a lock-in sub-par alternative. The platform became a commodity; nobody could own it.
Which is where we are now, and what this article depicts. You still need a management strategy, k8s doesn't change that. But now everyone's management service has to compete on its own merits. Nobody gets to play the lock-in game.
Google's management service is GKE. It's good, but not because Google started Kubernetes. Rather, Google started Kubernetes because Google has the expertise and experience to make GKE good.