Why do I need an additional player device if I have a Roon nucleus and a dac?

Thanks all and especially drrsutliff.  Streaming equipment can be abit challenging to understand, and it don’t need to be.  So easy to make a purchase mistake, etc. 

Two scenarios where you would need a separate streamer

1 is if you wanted to use a service that wasn't supported by your Nucleus (Spotify, Amazon, Pandora) and did not want to connect a PC to your DAC.  As long as you are using your library and Tidal or Qobuz you are good. 

2. The one other scenario (and I face this) is if you can get an ethernet connection close to your system.  My ethernet is 20' away and in a closet and adding a hot spot has proven challenging.  Unfortunately the streamer I chose is not a proper Roon endpoint at the moment (Chord 2Go) and I am stuck connecting to it via airplay.  I am irritated with Chord at the moment (and Roon).  There was no need to implement this certified endpoint restriction in the middle of COVID 19.  

Thanks verdantaudio,
great info.

i will likely get the nucleus.
my Ethernet occurs by splitting the incoming tv cable, supports modem and tv.  A hole in floor is how cable comes into room. Also, via router I feed Ethernet to this room and a downstairs room via hole in floor.   

Based on the reviews I have read, I do not consider the Nucleus overly expensive for what you get, and the build quality.  If I ever needed to replace my Antipodes DX I would not hesitate to consider a Nucleus Plus with an internal or external drive.

Regarding, endpoints, the Nucleus can serve as both renderer and endpoint, as can my DX, and that will be great for many listeners.  However, in addition to the reasons given above, the reason I use a separate endpoint is sound quality.   I use Ethernet to connect my server to my endpoint and then use I2S to my DAC.  Between my server and endpoint, I use two TP Link optical converters to optically decouple the Ethernet connection.  The end result sounds better to me than running the whole thing through the DX only.

You can for sure use JRivers26, Almarro or others as well as Qabuzz, Roon with your pc .what I do highly recommend and truly an upgrade is the Jcat femto usb card, as well as femto ethernet 
card a world of difference ,for not only uses the best commercial femto clocks but regulators and isolation from the computer noise
from the musical signal .easy to install and a highly recommended.
just see excellent reviews .