@Charred - Balance is important in bodybuilding, but imbalance sometimes results from other activities.
For example, in sports you sometimes have what’s called an overuse injury – where one muscle gets used a lot, in a particular motion.
You can find this in tennis for example. I know this because my son developed tennis elbow as a result of playing tennis and the repetitive motion involved with the swings of the racket.
We eventually had to get him this tennis grip rotation device that manipulated his tendons. It moved the muscles back and forth; in effect, it used both agonist and antagonist muscles as part of the exercise, to restore muscle use back to his arm.
It worked well; he now scarcely feels any pain while playing tennis.