Summary: It's cheaper, safer for handling sensitive data, easier to reproduce results (only way to be 100% sure it's reproduce even, as "external" models can change anytime), higher degree of customization, no internet connectivity requirements, more efficient, more flexible.
No ridiculous prohibitions on training on logs… Man, imagine being OpenAI and flushing your brand down the toilet with an explicit customer noncompete rule which totally backfires and inspires 100x more competition than it prevents
"Llama 3.1 materials or outputs cannot be used to improve or train any other large language models outside of the Llama family."