What's the point of a baby monitor?

Wow there are a lot of options! I’m trying not to be drawn into the baby-industrial complex hype dictating that I need a fully featured baby monitor that spews so much telemetry that it can be used to monitor the vital signs of astronauts. So really what’s the point? I suspect it’s for elementary remote monitoring: the little dude is crying so I better go upstairs and see what the malfunction is. Is really just for convenience?