"simplified" things with Docker and k8s.. if you are using docker for anything other than microservices and development environments you are doing it wrong.
Containers are substantially different to VMs, but in practice I see them as equivalent technologically and operationally for my home lab/self-hosting use cases (sans weaker security guarantees, but that I can live with).
They are a simplification in practice, because I can toss everything into a bunch of Pis that stay on 24/7 rather than worry about the power use (and the power bills) that would come with using a more fully-featured rack server/old PC that has enough RAM to deal with multiple VMs.
Containerd then? Containers predate docker in the form of VMs, the only difference being optimizations with not having to run another entire OS kernel to get software running in the exact same state on many machines in just a few seconds.
They are a simplification in practice, because I can toss everything into a bunch of Pis that stay on 24/7 rather than worry about the power use (and the power bills) that would come with using a more fully-featured rack server/old PC that has enough RAM to deal with multiple VMs.