Because people like you continue to try to spin something different than what Apple says about this topic themselves.
And I'm not claiming it's a mono speaker. It seems only those who want to spin one as stereo or more-than-stereo keep seeing challenges to those ideas as others calling it mono. Personally, for reasons beat just about to death in other threads, I'm (personally) in the mono+ camp myself.
And again, if all it takes to be able to formally call it "stereo" is one more woofer, why is Apple saying it will also need a software update in their copy about "it takes two" for stereo? One will have that second woofer as soon as they buy a second HP. Is Apple wrong for saying it needs a software update too?
People are saying a single HomePod is not stereo. The basis for this is Apple allowing you to pair two HomePods as a stereo pair.
This is absolutely false. A single HomePod can output a stereo signal. It won’t have as wide a soundstage as two speakers placed far apart, but it’s still stereo.