Here's why:
* Adjectives describe nouns: They tell us more about the noun they modify. For example, "blue car" tells us the color of the car.
* Names identify individuals or things: They don't describe them. For example, "John" is a name that identifies a person, but it doesn't tell us anything about him.
Example:
* Incorrect: "The John car is red." (John is a name, not a descriptive word.)
* Correct: "The red car belongs to John." (Red describes the car.)
However, there are some exceptions:
* Descriptive names: Some names are actually descriptive words, like "Mountain View" or "Red River." In these cases, the name acts as an adjective.
* Proper nouns as adjectives: A proper noun can be used as an adjective to describe something related to the noun. For example, "Shakespearean plays" refers to plays written by Shakespeare.
In general, it's important to distinguish between proper nouns (names) and adjectives.