" . . . I know I’m missing something here, probably ?"
@robelvick Apologies if I misunderstand your question. Years ago, DAC’s did not have a USB input. They only had a coax, optical or AES/EBU connection to talk to the CD transport. When computer audio began, a ‘bridge’ component was needed for the DAC to talk to the computer – instead of the CD transport. This ‘bridge’ component had a USB input from the computer - but had a coax, optical or AES/EBU output to connect to the DAC. Over time, this ‘bridge’ component has evolved into a multi-featured ‘streamer’. Also, all new DAC’s have USB inputs. The bottom line is that streamers greatly improve the sound quality. In my system, I use an Empirical Audio Off-Ramp 5 from my laptop to my DAC. Music from Tidal sounds as good as my high-end CD transport.