Model weights are source because they are "the preferred form for modification", e.g. you can use them for fine-tuning. Training a new model from raw data (1) gets you something very different from the original and (2) is computationally unfeasible for most, compared to simpler fine tuning.
I disagree. Fine-tuning, while useful, feels more like patching executables than source code. Besides, just because most people don't compile e.g. Android for themselves doesn't mean that Android should only be distributed in binary form.
