Why does a Music Server require high processing CPU power?

I noticed that some music servers use, for example, a dual multicore CPU’s running under a custom assembled operating system.  In addition, the server is powered by a linear power supply with choke regulation and a large capacitor bank utilizing the highest audiophile grade capacitors.  Various other music servers have similar high CPU processing capabilities.  

I know that music is played in real-time so there is not much time to do any large amounts of processing.  I also know that the data stream needs to free of jitter and all other forms of extra noise and distortion.   I believe that inputs and outputs are happening at the same time (I think).

I also know that Music Servers needs to support File Formats of FLAC, ALAC, WAV, AIFF, MP3, AAC, OGG, WMA, WMA-L, DSF, DFF, Native Sampling Rates of 44.1kHz, 48kHz, 88.2kHz, 96kHz, 176.4kHz, 192kHz, 352.8kHz, 384kHz, 705.6kHz, and 768kHz and DSD formats of DSD64, DSD128, DSD256 and DSD512 including Bit Depths of 16 and 24.  

Why does a music server require high processing power?   Does the list above of supported formats etc. require high processing power?  Assuming the Music Server is not a DAC, or a pre-amp, what is going on that requires this much processing power?   

What processing is going on in a music server?  How much processing power does a music server require?  

Am I missing something?   Thanks.   

I just got a Hi-Fi Berry Digi+ for my RPi3; Hoping to configure this soon. Did you have any issues with the setup you can share?
I'm setting up another roon endpoint system in the house and had an RPi laying around. 
+1 to those who say the best they have heard digital sound is through a dedicated Roon core--in particular the Intel NUC running Roon ROCK.  

This blew me away. I've always streamed Tidal to a Bluesound Node and shot the digital algorithm out to a DAC.  Well, going Roon ROCK (Intel NUC) right into the DAC is like buying a real upgrade!  No foolin'.  This is the best $500 I've spent. 
@jbhiller absolutely! 
Roon ROCK has been incredible. 100% stable no variation in SQ, no performance issues, lagless UI experience; best of all, the SQ is crystalline pure.
I now never use the MConnect/UPnP option on my ethernet DAC; Roon is fantastic!
I can only hope that future software updates retain the excellent SQ; 

For another system, I finally setup my RPI3 with a HiFi Berry Digi+ to use as WiFi (or hardwired) Roon Endpoint; Majorly impressed with this hardware and configuration over internet browser;