I have been reading that Vagrant provides a out-of-the-box support for docker after version 1.7. So, it seems this will be easier, and with an obvious case for

I have been reading that Vagrant provides a out-of-the-box support for docker after version 1.7. So, it seems this will be easier, and with an obvious case for Windows or Mac. I am already on Linux, so, my question is why create extra abstraction to it? Is not the function of docker to provide isolation as Vagrant but without the extra overhead of VM. As far as I could gather, one prominent use cases of Docker is the cheapness. Would not doing Docker on top of Vagrant beat that purpose?