@erincandescent Infidel, if they didn't do that, people would just modify the GPLv3 into a proprietary license and say that such proprietary license is the "GNU General Public License version 3".

Permission to modify the license has been granted, provided you remove the preamble and any reference to GNU and the FSF: https://www.gnu.org/licenses/gpl-faq.html#ModifyGPL

This is quite unique for licenses - as most license authors refuse to allow for any modifications, very much so including pushover licenses (some are so short that they don't qualify for copyright, but there are a few longer ones that are creative enough that copyright applies).