Is benzene harmful to human health?
As Ivan Neretin commented, parts of a compound can never dictate its own properties to the entire molecule's properties. Additionally benzene is not a very effective functional group by itself.

In short, a restricted use is only applied when that certain chemical is exposed by itself. In paracetamol or any other thing including benzene, you will not see any benzene vapor emanating from them or something. It would also be meaningful if benzene containing compounds degradation products included benzene, like in environmental degradation of chlorobenzenes, though this is not a usual case as I see.