Amazon and I guess Siri's original design was completely undiscoverable. Both had limited vocabulary and actions you could take. I had to learn from others what I could even ask the devices. Also both were audio only and for things like, "turn on the lights" that required talking to cheap 3rd party devices that barely stay connected, it was frustrating.

Instead of quickly iterating to find how to take voice to the next level, both projects quickly locked in on whatever that was and became too costly to pivot.