The author seems to have spent the better part of a decade working professionally with Postgres. I think editorial choice, rather than ignorance, might be why they’re not mentioning more prior art.
In this blog post, we wanted to focus on running Postgres for others. AWS, Azure, and GCP's managed Postgres services, and those offered by startups like Crunchy, don't use k8s-based solutions. For us, one reason was operational simplicity. You can write a control plane for managed Postgres in 20K lines of code, including unit tests. This way, if anything breaks at scale, you can quickly figure out the issue without having to dive into dependencies.
We also understand different tradeoffs apply when you're running Postgres for yourself or for others. In this blog post, we wanted to focus on the latter scenario.