As I was trying to understand this space coming from a 'docker user' background I was incredibly confused by the two different definitions of "privileged containers" ("what do you mean if I don't add --privileged it's still privileged?") -- so I figured others might appreciate the pointer as well.

Now that I understand what's going on better, I definitely agree that docker does not abstract the kernel APIs in a way that makes it easy to understand what's going on underneath the hood. Is that a good thing? I honestly don't know.

I'd encourage anyone interested in learning more to check out the codebase for JessFraz's contained.af

You nailed it. If you can take a hard to grasp or orchestrate concept and make it easy for the layperson to use, then you've built a linux tool