Cables can matter, when their impedance (of which only resistance is of practical relevance) is comparable to the resistance of the circuit with the transducers, 1/8 is a good well-known/cited rule of thumb.
Now, many IEMs, for instance, have impedance below 16 Ohm, even below 10 Ohm (do not ask me why), and typical stock cables can be easily 1.5-2 Ohms. So when someone changes stock cable for the cable of the significantly lower resistance (0.5 Ohm or less) - the difference is there.
This difference can be even more drastic for multi-transducer IEMs, such as multi-BAs, with transducer resonances, where their impedance gets lower.
There changing the impedance of the cables can appreciably affect the frequency response.
I hope I am stating fairly obvious things for this forum, just to point out that "cables matter" can be quite real sometimes.
Another story is when "graphene" cables are sold to poor audiophiles