I'd argue that bocker makes that more clear. It takes away any idea that the magic is in the containers. To the degree that it is, Linux provides that...not Docker.
It helps focus on what Docker does provide, as you mention.
Right that's a reasonable claim. bocker makes false claims though, which causes a bunch of confusion (which seems to be the case for the person I was replying to).
"Docker implemented in around 100 lines of bash."
This is simply not true.