Good observations.
It seems to me that it is not inconceivable that noise coming into a DAC over the cable might affect the conversion and analog circuitry. It is not impossible, open to proof either way. Although I hold the position that if so, it is a failure of the designer of the DAC, it should provide isolation and jitter reduction.
Just like it is not inconceivable that power cables matter for any electronics including amps. Open to proof. But it would be a failure by the amp designer.
But I am quite convinced that whatever the effects you may note with USB or IP cables, they are not caused by bit errors. Not just because the protocols have error correction (because why would computer engineers have designed stuff that was prone to bit errors?). But because that’s the central difference between digital and analog, you don’t have to measure the voltage exactly, you only have to distinguish between a few distinct values.
I think you are right, much of this is probably rooted in a love for a the good old days of analog. Problem is, we don’t know if all of it is.