The human animal has not changed in long time , how much better than we can hear do we need ? even a 30 year old CD player is better than humans . So it has nothing to do with progress of science .
However there are reasons for for better than human performance EQ and room corrections system . for example in my headphone rig i sacrifice -10dB in digital gain to accommodate the EQ and the extra headroom to avoid issues . And in the maths for filters and EQ in products with them inside , there you want better performance .
The DAC + amp is dead quit anyway even if i toss away 10dB. I dont hink a phone dongle would and i would not drive the headphones very well .
The test OP did was a very easy on the phone dongle it only had to provide voltage not driving headphones , in that limited capacity it performed "good enough" aka better than most humans .
Also . if you use DAC with digital volume controll as a preamp , depending on amp sensitivity etc , there may be very good reasons to step up from a phone dongle . It cost more but it does not need to be a dCS stack either .
On the other hand high end is filled with products that performs much much worse than a phone dongle . The TotalDAC ? every NOS filterless dac ever sold . Audio Note ?