Exactly. If you had a mixing desk like the one I use you could absolutely do away with your audio interface and use this as your sole audio interface.
The Soundcraft Signature 12 MTK has something called “USB Return” so you can select the output of any fader to be either the input that is plugged in to the channel of the computer assigned output number for that channel.
I still use a Scarlett 2i2 in my setup and have it plugged into a mixing desk channel. The reason for this is I get a very simple “what you hear” feed from my iMac on one fader for when I’m live streaming.