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.
Hating on CrossFit is trendier than those hipster Ray-Bans your aunt bought you. There are some aspects of CrossFit that deserve your attention, however.