The term is mostly used for speakers with a built-in assistant (Google Assistant, Alexa, etc.), where the assistant is one of the main reasons for wanting a smart speaker.
It's great for things like setting alarms, kitchen timers (don't have to touch anything with your hands, just talk), checking the weather, and controlling the other smart devices like lights, with just your voice.
People clearly get something out of these and they've been around for a while.