Not everything can be counted, counts. Not everything that counts, can be counted.
You can’t judge a speaker by just the freq. response graph. Same for cables.
Yes, if there are some obvious anomaly in the freq. response, then sure you can say it’s a bad speaker or cables, but within some acceptable range, measurements cannot separate the bad from the good.
The problem is 99% of the speakers or cables on the market all fall within the "acceptable range". Only listening can tell.
If you think you can measure a cable freq. distortion and can tell the good and the bad, you may as well spend your time watching paint drying.