All devices that contain time of day displays. I live in 800 square feet and with appliances, clocks, etc. There can be 4 minutes difference across 25 feet.
What about the users who need to get account related email that they signed up for? I understand your disdain for unwanted email, I share it, but why should our opinions have a negative effect on others.
I had one of these on my desk in 1984. It was very usable.
As for having more than one on a desk, you had better have a really well built one. As I recall, it weighed about 75lbs.