The truth is, they actually work better than most other exercise machines.
The reason for that, is that they work more than one muscle group at once. Think about it. You’re working both arms and both legs at the same time.
Compare that to perhaps the three most common exercise machines out there:
An exercise bike, which only works your legs in a small degree of motion.
A rowing machine, which has a good range of motion but still only works your upper body.
A treadmill, which has more dynamic movement to it, but it only works your legs and it doesn’t even provide resistance against you.
As you can see, a vertical climber is basically able to do the same job as all three of those machines at the same time. This is why we harp on all the time about climbing being such a great alternative to the gym.