Using virtualization technology to actually to abstract away hardware hardware and OS differences? How is that an edge case. Isn't that the raison d'être of virtualization. That fact that host and guest OS kernels happen to match is the edge case then (a nice one too, that can lead to good optimizations).

Now deployment, isolation, repeatable test and dev environments is a bit of a different beast. So LXC works great there.

The point was to avoid the conclusion that KVM is useless now in all cases, throw it away tomorrow and start using LXC.

Would you consider it edge-cases to run Linux-instances on a Windows Hyper-V based server? Would you consider it a edge case running a Windows VM in Linux?

I certainly wouldn't. Those are definitely what I call "general" virtualization cases.

And as awesome as containers are, they wont be able to cover for these cases. It's definitely worth mentioning for those who are not familiar with the matters.