The benefit is that no single part of the system has too much power, in other words everyone has equal power.

The benefit of everyone having equal power is that no one system can dominant and have full authority of the country. Each branch checks each other to make sure that the powers aren't abused. Having equal power was initially placed in the constitution because it prevents the United States from having a king and being placed in the same situation that 13th colonies left. Equal powers makes it so that not one person or party can be judge, jury, or executioner.