Namespacing and isolation also unlocks additional features, such as VM-style checkpointing and migration (via the CRIU featureset, which AIUI is now part of the mainline kernel). Moreover, the 'container' workflow provides a common interface that the various sorts of orchestration/deployment/management platforms can then rely on.

> I personally like the isolation they provide and generally prefer running services in containers, even if they are using the same dependencies as my OS.

I would also not downplay the importance of Docker's support for software-defined networks and it's ability to arbitrarily configure networking at the container level.

I firmly believe that networking doesn't pop up so often while discussing Docker because Docker solves that problem so fantastically well that a complex problem simply ceases to exist and completely abandons everyone's mental model.

Having to define complex networking completely internal to a server is a problem that docker created, not one they solved.

Have they fixed ipv6 support yet?

Yes they have, but there is also a plethora of other container daemons and tools now aside from Docker with IPv6 support.