Misinterpretation: Simulation Training
Too often an exercise is chosen or developed because it resembles an activity we want to improve (sports movements, everyday activities, etc.) What we fail to recognize are all of the things we can't see within that exercise that actually make it dramatically different from the goal-activity, often to the point of becoming detrimental to performance... or even the body!
Conversely, an exercise that looks nothing like the sport or activity can provide benefit to an integral link, and while appearing totally dissimilar to the activity actually improves components that are vital to the performance.
Along the way "functional" has become the unjust condemnation of some exercises and the undeserved glorification of others. -