If the constitution is carefully crafted to restrict the power of the state, and the power of the state has steadily grown to its now unprecedented levels, did the constitution fail or did we fail the constitution?...

Despite Mosca focusing on a parliamentary democracy in this passage we can see the parallels to our own system. The other branches become bureaucracies in service to the legislative branch which is seen as the most legitimate power because it is selected most directly by the people. When popular sovereignty is the only legitimating force in society, the most democratically elected branch is seen as the most valid. It makes all other branches subservient and they are eventually made subject to the exact same selection pressures. No other social force is considered legitimate, and so manipulation of public opinion becomes the key to ruling the entire state.