JACK has been a long, strange and wondrous journey, and even if at this point I lean towards thinking that the whole idea was a bit of a mistake (! :),
Definitely not. I guess you were thinking about some sub parts of jack when you wrote this.
Firstly, jack provided a simple to use API to send and receive audio with low latency to and from the soundcard.
Secondly, it made it possible for several programs to access the soundcard simultaneously,
so you didn't have to start and stop programs all the time.