Depends on the device.

Something like a vacuum, sure. You’re probably going to move it around anyway.

But I used to have a Spectrum computer, and it had no power switch. If you plugged it in then it was just on. Much simpler to power off at the switch than unplug it and risk the plug falling down the back of the table into a rats nest of cables.

Plus I guess it’s one more step a toddler needs to do to electrocute themselves…