Not if they are smothered and/or can't lift their head yet to breathe. Newborns are very weak in the neck and generally struggle to lift their heads.

We had a wireless monitor that velcroed around their foot that monitored heart rate and blood oxygen level (Owlet brand). It went off once after an ill-fated breast feeding session at god-knows-when-o'clock where they got into a weird position between a very very drowsy mum and some cushions and we didn't notice. Would they have suffocated eventually, or maybe they would have mustered a cry? Who knows, but I am glad the alarm went off and we were able to wake up mum and reposition the baby so their face was not mushed into skin.

For us the monitor was something that allowed us to relax a bit.

It also had the added bonus of you could tell if they were getting a cold before they had any other symptoms as their heart rate was usually higher than normal when they were sleeping. Very useful.

I take it you've never actually cared for small children. One of the most obvious problems they solve is the ability to go outside earshot of the nursery - doesn't matter if the kid cries if you can't hear them! Besides that, kids often cry temporarily and then go back to sleep like 30 seconds later. It's very convenient to be able to detect if that's likely to be the case without having to walk across the house and open their door.