When rehabbing an injury it's important not to lose sight of your goals. Many time in traditional, old-school thought of rehab, the clinician and patient get so focused on individual muscles to be activated they fail to recognize the dysfunctional system, hence the "forest for the trees" comment.
Rehabbing individual muscles does not make a dysfunctional system functional. that sort of thinking would be no different than thinking a replacing the engine of a rundown old junker suddenly makes it a hot rod! There can be some muscular rehab for some injuries but to apply that to all scenarios and limit rehab to isolated muscle activation would be ineffective.
The emerging trend in rehab is to train the system. The muscles you would normally rehab have to function appropriately within the system they are a part of in order for the system to be efficient. Therefore it only makes sense to train the system as a whole.
In order to do so, you have to remove the stress of being upright, weight bearing. If/when the system fails in weight bearing you take it down to non-weight bearing, like kneeling or sitting. If that is still too much for the system take it down further to a suspended spine (hands and knees). And if this is still unstable then you take it back to the most basic of positions, on you your back. From here you are in the simplest of position and have removed all postural stability requirements. In this position you can perform any exercise without a need for postural stabilization, allowing the brain to focus on the unimpeded motion in the joint. Once you can perform proper ranges of motion without pain with stability, you start climbing the ladder back to standing.
For some people even laying on their back is unstable. For those folks, we focus on breathing, because when the diaphragm isn't being utilized as designed, nothing can be stabilized. It may not seem like much but relearning to breathe with the right muscles is the foundation of spinal stability which is necessary to achieve extremity stability.
Anybody can get by without stability for a period of time but eventually, the compensations will fail and the system fails. This is where you start noticing pain, some worse than others. At the point of pain you know has dysfunction, to postpone rehabbing said dysfunction means you move in pain regularly which also means you move differently in an attempt to reduce painful movements. These compensation further destabilize the system and only prolong the road to recovery.