Dips are more pre-disposed to producing dysfunctional mechanics than most upper body exercises. When performed incorrectly, dips will wreak more havoc on the shoulders than just about any other movement.
However, when executed with perfect technique and appropriate body adjustments, they're actually therapeutic on the shoulders. It's important to master the correct form in order to reap the worthwhile benefits while avoiding the potential drawbacks.
There's a difference between mobility and stability. Mobility is the ability to produce a desired movement, while stability is the ability to resist an undesired movement. Knowing the difference is the key to performance.