Spotify Connect Volume Control: Operating in Series?

Spotify Connect using the volspotconnect2 plugin seems to work with a ‘cascading’ volume control, where the volume control in Spotify operates on the sound volume level before or after the main Volumio volume control. That is, the volume remains quite low when either of the controls is very low and the other is high.

I am just wondering why this is so. Doesn’t this detract from the audio quality? I assume the audio from Spotify’s servers is the original bitstream and it should just be decoded and directly amplified, without a second volume control. Since I assume Volumio receives a chosen volume level from Spotify’s servers upon choosing volume via a Spotify client, shouldn’t that value just be synchronised to the Volumio volume control? I believe other devices with Spotify Connect work that way.