Docker uses the same kernel primitives as other container systems. But it tied together cgroups, namespaces and stackable filesystems into a simple cohesive model.

Add in image registries and a decent CLI and the developer ergonomics are outstanding.

Technologies only attract buzz when they're accessible to mainstream developers on a mainstream platform. The web didn't matter until it was on Windows. Virtualization was irrelevant until it reached x86, containerization was irrelevant until it reached Linux.

Disclaimer: I work for a company, Pivotal, which has a more-than-passing interest in containers. I did a presentation on the history which you might find interesting: http://livestre.am/54NLn