http://en.wikipedia.org/wiki/Solaris_Containers
Of course, Solaris is even more despised by some people since they changed hands.
I think Docker appeals more to people, because:
- It's on Linux, which is more popular than FreeBSD or Solaris.
- It's very easy to set up and configure.
- Integration with Puppet et al.
- The have great marketing :).
Docker took a technology known to many that setup/admin/manage machines, added some fluff, made things simpler, and marketed the idea.
In a crowd that might spend more time thinking about nodejs and callbacks vs promises or how easily one can tip a rails app up on heroku, existing systems tools for things like jails/virtualization may either be over looked or not a concern.
For every docker, there are people (of which I may be one) that think , "big deal, it is just x". Meanwhile that thing is getting traction and popularity. It might not last, but it is around and making noise now.
(You could say same about Github, Travis etc.)
Well what on earth do you need a pre-assembled computer for? You just take some circuit boards and a soldering iron, then assemble everything over the weekend and you have a perfectly good computer. I don't understand why this Apple I thing is so popular, it's nothing special.
Far as I can tell, every successful piece of tech out there can be reduced to "Added some fluff, simplicity, and marketing to an already existing technology"
And I think that's the crux of it--do you think anyone would use Heroku if its container environment were FreeBSD-based? I'm guessing not; nobody develops on FreeBSD, so they'd have to test on a separate FreeBSD VM before deploying.