Note that this is not the case for virtual kubelet-based implementations, and your point here and above are specific to how Kata works (the article is talking more generally).
Yeah.. I think I see what you say, I mean, the end user interface is the quite the same but this has big implications anyway for the systems design POV, so is not a small thing :)
It's not all or nothing either. Containerd will support running a mix of containers and kata-containers across workers.
For anyone interested in this topic I wrote about some other container runtimes here: https://kubedex.com/kubernetes-container-runtimes/