even if you are trying to strengthen those muscles for the sake of a sport, something like lateral lunges would be a much better choice.
Sure thing! Having said, I have never used those silly machines to train the adductors and abductors. I've found that single-leg side planks are one of the best exercises for more isolated adductor work. Especially if you elevate the supporting foot. For abduction I'm a fan of side-lying abductions with sligth variations. Lateral exercises and for example lateral lunges with a cable hold (like in pallof press) are awesome as well.
To say that the main articulation of the hip is adduction/abduction is silly. When do you need specific adduction/abductor strength in real life? Very rarely. I admit some people migth benefit from working those movements, but then there is usually found weakness or dysfunction or something similar. Consider adductors and abductors more like stabilizers. They prevent unnecessary movements when doing bigger exercises. So they work on almost every exercise making sure your knees won't collapse or go too wide.