Although a license like the GNU GPL or a simple license like the one in the Free Music Philosophy can make use of copyright law to achieve unrestricted distribution, that is a pragmatic position taken in consideration of the views of people who may wish to implement it.
I myself have personally taken a more idealistic and extreme view in that all information I publish is freely copiable without restrictions. I do believe credit should be given where it's due and I appreciate it when it is given.