The reason why people go distances to package PyTorch is because the skill of translating models between different frameworks manually is "easy" but not well dispensed in developer community.

That's why people will go stupid lengths to convert model from PyTorch / TensorFlow with onnxtools / coremltools to avoid touch the model / weights themselves.

The only one that escaped this is llama.cpp, which weirdly, despite the difficulty of model conversion with ggml, people seem to do it anyway.