I think the objective "scientific" arugment is that as long as the characteristics of the circuit are compatable with the characteristics of the cable used, the signal will get from point "A" to point "B" with no degradation. A couple of good examples of this are loudspeakers, when using a cable that presents significant resistance in propotion to the speaker's impedance, causing frequency response errors. Another would be using an interconnect with too-high capacitance for the impedance of the circuit, causing high frequency rolloffs. These are the big ones, but there are others, especially when sending higher frequency stuff like digital audio bitstreams, and especially video, which gets extremely cable-critical.