Why is it necessary for a country to have a clear demarcation of powers and responsibilities in the constitution? What would happen in the absence of such a demarcation?

It is necessary for a country to have a clear demarcation of powers and responsibilities in the
constitution because:
 To ensure that no single institution acquires monopoly of power.
 In case of transgressions, it may be checked by one of the institutions.
 To specify who plays important role in decision-making powers.
 It shows how government would be constituted.
 It lays down some limits on the government and citizens both which are fundamental in nature
which should not to be trespassed by government and citizens.

 The Constitution shows how organs of government are interrelated along with a demarcation of powers of institutions like legislature, executive and judiciary as well as statutory bodies, ibsb Election Commission of India, etc.  The judiciary has been given a specific place to declare any law unconstitutional if not at par the provisions of Constitution. In the absence of such a demarcation:  The federal set up would get strained and there would be crisis in center as well as states.  There would be a problem to the citizens and laws will be proved to be unjust and unfair