Developer's mindset, knowledge and tooling is also a build dependency for any open source code. You can not realistically get the same code without it.
> you can not realistically get the same code without it
You mean the same source code? Because... I agree. That's why it's important for the source to be open. Both in the context of software and language models.
No, the same way training is not a build dependency for the weights source code. You can literally compile and run them without any training data.