Yeah: It forces parties to be broad-based and adaptable if they're going to compete nationally. It also avoids bizarre situations like France's 2002 election,

Yeah: It forces parties to be broad-based and adaptable if they're going to compete nationally. It also avoids bizarre situations like France's 2002 election, wherein the Left had to choose between Chirac and Le Pen (something similar is not improbable in 2017, as well!)