> Correct me if I am wrong, but with GPL the only requirement is to
> provide a copy of the GPL with the source, so the only one who is
> mentioned is the FSF. Hope they are getting the economic benefits :-)
Take a look at section 1 of the GPLv2 or section 4 of the GPLv3. They require that you keep
copyright notices intact when distributing copies.
Furthermore, section 2(c) of v2 and 5(d) of v3 extend this to interactive programs. If the
program displays a copyright notice to the user when run, it is a breach of the license to
distribute modified versions that remove said notices.
So removing attribution is also a breach of the GPL.