Stepping back for a moment… you see digital interconnects in high-end pro audio gear, using systems like Dante. These systems are NOT simple. When you have multiple digital audio systems connected together, you have to worry about whether they are all running from the same clock, or whether you can convert from one clock to another. Systems like AES solved this by having “word clock” running on separate coax cables with BNC connectors.

If you look at consumer digital audio stuff, like Bluetooth speakers, you find all sorts of weird problems. It turns out that for cheap consumer gear, you get better quality audio from simple analog connections anyway.

If you want speakers with digital inputs, you also need to power those speakers. That uses up more power outlets.