Why is there a “temporal dead zone” in ES6?

In ECMAScript 6, accessing a let or const variable before its declaration (within its scope) causes a ReferenceError. The time span when that happens, between the creation of a variable’s binding and its declaration, is called the temporal dead zone. For more information, consult Sect. “The temporal dead zone” in “Exploring ES6”. Here, I’d like to answer two questions: Why is there a temporal dead