The author is pointing out that many programs duplicate OS virtual memory functionality by paging temporary data to persistent storage and loading it when needed. This duplicates the operating system's built in virtual memory capability and has negative effects on the system. The whole idea of virtual memory is to allow a system to handle loads where memory allocated exceeds the size of RAM.
> Modern systems don't necessarily even have swap (looking at you, k8s)
Modern linux does have swap, and it is quite useful. Proper support for swap is coming in k8s (looks like 1.23). Quite a few workloads need swap to run safely, so adding this to k8s will be an improvement.
> This is also written terribly.
Bad joke was bad.