Is delegation a motivational tool for people to realize their full potential, or a way to shoulder blame onto subordinates?
It is not really possible to say that delegation is one or the other of these. Delegation is, like a lot of things, something that can be good or bad depending on how it is actually implemented. In the hands of some managers, it can be a good motivational tool. In the hands of others, it can simply be a lazy way out of working and taking responsibility.
Delegation in and of itself is neither good nor bad. What is good or bad is the way in which the delegation is carried out. A good manager will delegate carefully. Such managers will think about what tasks do not need their personal attention. They will try to take tasks that can safely be delegated and match them up with subordinates whose skills will be a good match for those tasks. Bad managers will delegate more haphazardly. They might, for example, simply take the tasks that are hardest or least interesting to them and slough them off on subordinates in a random manner. This does not help motivate subordinates nor does it help them to grow into new responsibilities.
Delegation, then, can be either good or bad depending on how it is carried out by the manager.