Novice Question: Dedicated Streamers


Basically, I’m confused as to what function a stand-alone music streamer without onboard storage serves.  I know I’ve got some sort of glaring, mental blank spot about this.....the only thing I can figure is that there is some sort of enhanced music file processing over what one gets with most home computers and storage happens by plugging an external storage drive(s) to this sort of component??  Can someone enlighten me better about these?  The Blue Sound “Vault” has caught my eye of late but I’m wondering if I might be missing something by not looking at the “node” by the same company.  I don’t anticipate ever using any sort of music subscription service if this is important...  
lg1
This all clears up a lot for me.  Thanks, all!  Prob. For the foreseeable future, I’ll continue to stream tunes from my Mac > Airport Express....I’d eventually like to acquire a better DAC and go wired rather than wireless (rare dropouts but they do happen when the microwave oven is running!).  It all sounds pretty wonderful now, as is but...well...upgrade-itis lol.
I think the OP query has been answered, I’ll just chime in with reiterating that streamers and PC based streaming are essentially similar.  Streamers remove the PC from the equation, but are in themselves computers with specialized OS.  There are are many theoretical advantages to removing the PC and using dedicated audio components.  Having done both, they both can deliver great sound.  Personally, since I stare at a computer screen all day at work, I don’t wish to be dealing with one while relaxing with music at home, but ymmv 
I started with a NAD USB DAC streaming from my Asus laptop mainly HiRes files & Spotify. I also like the Jazz 88.3 from San Diego State University and a few other internet stations. Loved the quality but wanted more convenience since my wife loves music but is not at all technical.

Decided to upgrade to the NAD C368, but use a McCormack DNA 0.5 as my main amp. The Dac and Preamp are wonderful and with the bluos system I get what I want and she gets a simple to use streamer setup for her use. Now I can add other bluos  components to customise the house. Planning next to add a NAS storage to replace the 1Tb drive plugged into the back of streamer and some bluos speaks in a few places where I don't do critical listening but want enjoy some quality music separately from other current music on the main system.

So far, am loving the combination of quality sound and convenience.  BTW I added a Spotify family account so she could use her account while I use mine in other places including around the house and on the road.