For the human body to function normally, each of its parts has to get enough oxygen and nutrients, otherwise organs will start failing, and eventually the body could completely shut down and die.
Temporarily it is possible to stop blood flow to certain limbs or organs, but if circulation is cut off for too long and the cells do not get required oxygen and nutrients carried via blood cells, and if they do not get needed protection they will start breaking down and dying. Failing parts can quickly spread an “infection of sorts,” where the decaying process can easily spread to other sections of the body. If blocked circulation is not treated, this can spread to the rest of the body and can eventually become fatal.
Too much blood in one place for an extended period of time can cause coagulation and thrombosis. Furthermore, thrombosis can cause stroke and failure of organ, which can lead to the death. On the other hand, ruptured blood vessels (regardless of a reason being an internal or external force) can cause escaping of blood, which can again lead to death.
Another blood disorder, anemia, can be caused by malnutrition. Anemia will cause fatigue, weakness, and a variety of other symptoms. In contrast, too much nutrients combined with lack of physical activities can cause clogging of arteries, which can obstruct normal blood flow, and again lead to thrombosis.
We can argue that certain body parts (organs/limbs) need more blood while performing different activities. For instance, when we digest food, exercise, or engage in an active thinking process, various part of our body may need more blood flow. However, this will happen only for a short periods of time, and afterwards the blood flow will return to its most optimal state, where there is a more or less uniform distribution of blood cells.
In our economic system, money has the same function as blood cells, and everything else goes the same ... flow in an optimal way is necessary, otherwise the system will die, taking down all of its components with it.