No, they have small slices across the spectrum. We need to keep those slices open to experimentation because of the need to be able to experiment and test a concept at different frequencies. Closing this off to experimentation stifles innovation.
Those frequencies are used all of the time but you may not be able to pick them up because of the lack of sensitivity of you receiver/antenna or they aren't being used in your area when you're listening.
On top of that, they're used for emergency communication. In my state (Montana) ham radio operators stepped up and help to save millions of dollars in property damage and quite possibly lives by allowing fire fighters to coordinate their efforts when the county's repeaters got burnt down. This was recognized by state government and hams were exempted from distracted driving laws so they could continue to operate mobile.