What are the problems with presidentialism, according to Juan Linz?

What will be an ideal response?

Separation of powers as leading to “dual legitimacy”; since both the legislature and the executive are independently and directly elected, each has legitimacy. Since neither had a higher claim to legitimacy, there could be no democratic resolution of conflicts between them. Direct election of the president could lead to chief executives with a “winner-take-all” mentality who would overemphasize their national mandate and be less willing to compromise. Presidentialism is too inflexible: fixed terms mean that any serious problem for which a president might need to be removed—or even a president’s death in office—could provoke a political crisis.