By your reasoning I could use some 24 gauge wire that came with a pair of Walmart computer speakers with a receiver paired with 3-ways each with 10" woofers. Or even better yet, between a plate amp and sub as a fire starter.

I don't disagree with your overall premise, but it's too reductive, even for home theater. Throw in a "16ga in most non-sub applications" and only then does it become true.