The FAQ on the Creative Commons website states:
Can I apply a Creative Commons license to software?
We recommend against using Creative Commons licenses for software. Instead, we strongly encourage you to use one of the very good software licenses which are already available. We recommend considering licenses listed as free by the Free Software Foundation and listed as “open source” by the Open Source Initiative.
Unlike software-specific licenses, CC licenses do not contain specific terms about the distribution of source code, which is often important to ensuring the free reuse and modifiability of software. Many software licenses also address patent rights, which are important to software but may not be applicable to other copyrightable works. Additionally, our licenses are currently not compatible with the major software licenses, so it would be difficult to integrate CC-licensed work with other free software. Existing software licenses were designed specifically for use with software and offer a similar set of rights to the Creative Commons licenses.
While we recommend against using a CC license on software itself, CC licenses may be used for software documentation, as well as for separate artistic elements such as game art or music.
This seems to recommend not using any CC licenses for software. But the reasons for this recommendation listed in the second paragraph do not seem relevant when examining a software license such as the MIT license. The MIT license does not mention source code or patents and the CC-BY license seems compatible with the MIT license. For me, this begs the question "How is using CC-BY any different than using MIT?" (with respect to the license's functionality). There must be a functional difference in the CC-BY and MIT license that would explain why CC-BY shouldn't be used for software.
This question is similar to the question:
but it discusses the CC-BY-SA license which has more complexities than CC-BY. This question does mention "License Proliferation" and I understand that could be a concern here, but since the CC licenses are so widely used I don't find it a compelling argument as to why not to use CC licenses. Thus, I'm interested in an answer other than "to prevent license proliferation" if there is one.
My motivation for this questions is that I have creative works that are collectively made up of software, images, written text, animations that I'd like to group and license in a liberal way. Applying the CC-BY license to the entire set of items in the work seems like the appropriate thing to do, rather than using the MIT license alone which is only for code & documentation or using multiple licenses for the different content types.
So, why does Creative Commons recommend not using CC-BY licenses for software?