As someone who did containers with LXC before docker, I think your characterization is off. The value in Docker isn't in the kernel features, but instead in the user space. Ever try Openshift 1/2, as painful as that was it was still better then rolling your own.

Docker's big problem isn't what's below them, it's whats above them. Their monetizing strategy has to involve the fortune 500, and right now, all of the momentum in that area is being eaten by Google with Kubernetes. Kubernetes has a very vocal faction that wants nothing to do with Docker, and replace it with something else.

Docker has plenty of challenges, but they have delivered significant value, most of which is still open source.