I think a big part of it would broadly fall under "legal and privacy concerns", especially since Apple Silicon is proprietary hardware. They need to work out which details about the hardware they might want to keep secret, and make sure the public documentation only contains things they're happy to share to the public. They then need to make sure it's up to their standards for externally published documents, it probably has to go through a review process, be published under a certain license which needs to be written or selected, and so on and so on.