Learning from source code is like learning from Photoshop files or Logic projects. Artists usually do not share them. In music, not even the labels get anything than the final mixdown (the music equivalent of the binary); the stems or projects remain with the studio - just like the source code in software projects tends to remain with the studios.
In software, we started showing and sharing source code under the assumption that it makes other humans making software better. People still rarely do this in music, as holding up industry secrets is deemed more important than fostering a community of personal growth.
We don't open source our code so an AI can grow. We do it so that humans can grow. There's no need to publish our code to distribute our final binary. This breaks the common understanding of why it's a good idea to share your source code, and as a result, people might become more protective of their code again.
In many ways, your comment is similar to all the comments saying "but you open-sourced it, surely you must know that people will then put it in their commercial code?"