Have been thinking about this for a couple years. I have old phones kicking around. Battery shot, hardware dated, but the camera(s) and mic and antennas still work. Would be cool if there were a way to set them up (powered) to stream audio/video or even take stills at intervals (or motion-activated) and then sync the content to the rest of the devices on my network.
I don’t know how complex the programming for something like this would be. But I suspect it’s trivial for those who do know.
There is no reason a camera cannot be on all the time other than power consumption. Why couldn’t it? The only limitation is software. Other parts of a phone can overheat from continuous operation (CPU et al., voltage converters, maybe flash LED and vibration motor) but not the camera.
Sensor wear, mechanical parts (if any), heat, etc. Essentially wear and tear. Just like nothing lasts forever, using it in a way that it’s not intended/tested/quality assured, may reduce its lifespan.
Basically: “is the device intended to be on and recording 24/7?”