it's very simple and no mystery at all.

There IS a given amount of parasitic properties to any cable.

Let's start with resistance. Resistance is audible in certain ways. In a speaker cable it will change the damping, Q. If you have an ohm of resistance then this might become audible. Q will raise. BUT if Q was low then the effect can be pleasant! I can tell you for a fact that it takes a mighty good pair of ears to hear even 1 ohm of resistance there. I can also tell you that a cheap 5 EUR. multimeter is perfectly well capable of measuring this resistance. There's the mystery cloud blowing over.... Please do measure the resistance of your tiny length of speaker cable once... That said in filter coils there is often a long length and here this resistance becomes more apparent and important to take into account. MUCH much much more than with a short piece of cable. Then resistance in line level cabling. I can assure you that on the average 1 meters length it is not making a difference. Also a speaker is 8 ohms on average, so here a 1 ohm raise is relatively significant. On a line level source the impedance of an amplifier input is 20K, 50K 100K. Now add one ohm.......that's with the input, then the output impedance, here it works the other way around. It's great for it to be low, but anything under 100 ohms presents pretty much the same a shorted input of the amplifier input. This will ensure low noise. Here the 1 ohm will also not be significant. Even on high output impedance passive guitars the 1 ohm difference will not be significant. In practise we are often speaking of milliohms instead of the 1 ohm example I'm using here.

Now capacitance. On speaker cables there could be capacitance... whooooey! Scary! I can tell you that the picofarads you may measure on a cheap piece of apehair speakercable you get with the average plastic cheap radio from the ALDI will NOT make any difference to the sound, on a good amplifier there are often capacitors of around 100pF on the speaker outputs to filter high frequent signals to prevent them from entering the power stage. Then on line level cabling. I can tell you on any active output the capacity, also maximally a few picofarads, will not make any difference at all, also here the inputs of an amplifier are often filtered with 100pF caps against HF interference. On guitar cabling on the other hand there is a significant difference audible from just a few picofarads of capacity. This will immediately influence the high frequency range. But then again often the cables for a guitar are several meters in length and the several Kohm impedance of a guitar element in series with a few picofarads parallel forms an inband lowpass filter.

Now inductance..... well I guess you can guess...

As long as you stay well out of these parasitics there's basically no difference in the audio performance. And as soon as you will you still may not even notice it because our ears are really not that great. That said there is this small twilight zone under which differences become VERY apparent (like when you literally disconnect the cable and make the resistance VERY high, or when you apply several hundred meters of cable length, like on coils or transformers. Or when you have a poor source, like a guitar... That said I can assure you that the green zone is easily reached and if this is as large as the whole earth then the red zone is actually not larger than a city.

This is all about audio, now video.

With modern SDI (especially HD-SDI!) or HDMI signals there is really high frequency signal being transported and a lot more can go wrong, but bless you with the fact that it is digital and when there are errors there will be degradation in quality. in 999/1000 cases this will not reveal itself in literal degradation, but shear drop outs. In perhaps this 1/1000 chance occasion you may have strange behaviour. And I have tested this a million times with VERY expensive waveform analizers where I work in our laboratory. Literally EVERY cable or product that our suppliers want to sell us is THOROUGHLY tested by our team of experts. And we do repairs for Sony they can't even perform themselves. They pay US to get certain repairs done! They even paid part of our equipment. Obviously I have a commitment to a certain form of secrecy to this kind of information, or let's put it like this, they don't particularly enjoy this kind of information to leak out. That's why I can't publish certain measurements.

I trust you see now that all this cable mumbo jumbo is just fed by the industry, trying to make people consume....