Really… that’s like saying all amplifiers sound the same… I am not sure Texas Instruments, Analog Devices, Cirrus Logic, Chord Electronics etc would necessarily agree with you, along with I suspect a significant proportion of the AES membership… (not audiophiles, but audio scientists and engineers in industry and research organisations).
To my ears DAC designs and converters do have differing performance characteristics, and it is the designer or manufacturer that has decided to focus on key characteristics … even the humble DACs in smartphones differ to my ears.
I think areas like crest factor, transient performance, linearity, intermodulation distortion, audio pass band, EMI and modulation are examples of areas that cause different audible characteristics.