Speaker / amplifier in question is all that you currently have in your player software + all the DSP + D/A converter + amplifier (+ speaker). Wireless through WiFi.
Especially it saves the complication of going to low level analog signal before amplifier. So essentially the amplifier is a “power DAC streamer”.
If source material is DSD, it makes full sense to send it as DSD to such system where you have a separate DSP engine specifically designed to process DSD content.