December 12 "The highest reward for a person's toil is not what they get for it, but what they become by it." --John Ruskin
As you well know, your muscles get stronger to demands of resistance imposed on them. Resistance and only resistance. It does not matter what provides the resistance. Whether it's a can of soup, a gallon of water, a resistance cable, a weight machine, or a free weight, a log, a barrel of concrete (shout out to Steve Justa) or even your own body weight, it's just another form of resistance.
So, what makes resistance cables so special? Truthfully nothing, you can build strength just the same with anything else in the list of resistance devices I mentioned earlier. Just like there are things a wrench can do that a hammer can't, there are some things that make cables more desirable than other methods of resistance. The smart coach or trainee learns the fundamentals and then can pick the particular tool that will meet the need at hand in the most efficient way.
There are more advantages, but these are the biggies. A good set up cables is less than one month at the most gyms. They can be stowed in a duffel bag or hung up when not in use.
Probably the best benefit is the ability to provide resistance in any plane. Whether you have cables that attach to something or have a set in which one end of the cable is in each hand, you are able to work virtually any muscle at any angle. This is nice for variety sake and specificity. If you train for sports such as wrestling or martial arts you can work standing or on the floor and mimic the sport motion with the cables.
Fred Crivello turned me on to cables years ago. Fred, an accomplished Jujutsu practitioner and coach uses cables to strengthen himself for Jujutsu and found them superior to weights for his needs. At the time I was lifting weigts a lot and really had not used many other methods of strength training. I had developed some overuse injuries and was looking for a change from weights. [Growing older and wiser has it's benefits:) ] Today I have different types of cables and they are a big part of the strength component of my workout.
For the person training at home, or if who has a busy travel schedule and needs a way to get a decent workout on the road, cables could be the anwer. It beats lugging the Olympic barbell with you to use at the hotel. I have read of people bring weights on a vacation with them, not athletes, but the bodybuilder type of folks that are in some cases addicted to working out.