Laziness, you'd sayIf you use the streamer volume control, you will lose bit-perfect playback. See here - https://faq.wiimhome.com/support/solutions/articles/72000593467-setting-volume-controls
The Fosi Audio V3 has a volume control, why not use it ?

I want the same convenience from Wiim (mini/pro/pro plus) connected to a DAC and then that DAC connected to Fosi v3. So my option is to have one singular remote / mobile to control the volume.