K8s always seems like the tool that people choose to avoid cloud vendor lock in but there is something to be said for C k8s lock in as well as the article points out.

If you end up with exotic networking or file system mounts you can just be stuck maintaining k8s forever and some updates aren’t so stable so you have to be more vigilant that windows updates.

I don't think it makes sense to conflate vendor lock-in with taking a dependency on a given technology. Do we then have "Linux lock-in" and "Postgres lock-in"? The term "lock-in" shouldn't be stretched to cover this concept imo.