In the sentence, "I want an air-freshener because I can't stand bad smells", why is the because-clause a subordinate clause? [duplicate]

The assumption that I can't stand bad smells is a coordinate clause because it is "complete in itself" is wrong. Coordination implies joining two (or more) ideas together that are equal in value. The grammatical glue to join them is contained in the mnemonic FANBOYS.

But the crux of subordination is to join two sentences together when one idea is less important (subordinate) to the other. And to subordinate one idea to another, we use a connecting word called a "subordinator"; because is one such subordinator.

In sum, the clause I can't stand bad smells is a subordinate clause introduced by the subordinator because.