Here's why:
* Adjectives modify nouns: They describe or qualify nouns. For example, "big" is an adjective in "big house."
* Determiners introduce nouns: They specify which noun is being referred to. For example, "the" is a determiner in "the house."
* "No" negates: It indicates the absence of something. For example, "No cats are allowed" means there are no cats permitted.
Think of it this way: "No" is like a switch that turns off the presence of something. It doesn't describe the thing itself, but rather its absence.