An article on "Exoskeleton Report" website, describes some differences between "exoskeleton" and "exosuit" in terms of disadvantage of soft exoskeletons as below:

Soft exoskeleton’s main drawback is the same as their main strength: they have no external rigid frame.  This means that the wearable device will have difficulty transferring power from any area of the body to the ground.  Motors and sensors will be more difficult to mount.  In addition, torque and force generated by actuators will enter the user’s body.  Imagine for example an elderly person that uses an exoskeleton to go the store and back, the exoskeleton will have to provide assistance with balance, stairs, entering and exiting a vehicle (currently no product on the market can do this but the technology is getting close).  A soft exoskeleton can provide the additional force to supplement the user’s muscles, but most if not all of that energy will go into the user’s body.  Elderly and disabled people already have weakened bones and muscles, so adding more strain to their body will be counterproductive.

• What is the problem with the lack of a rigid framework for transferring power to the ground technically?
• For example, in upper limb rehabilitation, what is the need to transfer power to the ground?