Internal systems are rules engines with hundreds of branches for the most seemingly simple claims. If every payer tried to encode the rules instead of the outcomes of those rules, it would also be entirely unusable, but for a different reason. There is no standard way to encode these contract rules. There aren't any constraints on the legal language that can exist within a contract. When CMS passed this regulation, lots of insurance companies were stuck with systems that flat out could not generate this output. They then had to pay millions to consultants to crunch historical data in order to create these files (which, by the way, is technically not in line with the regulation -- historical data should NOT be used to generate these files). CMS defined in painstaking detail the format and content of these files. Health insurance companies flagged to CMS early on that this would result in a huge amount of data, but at least at the end of it all you get a bunch of dollar amounts, instead of legalese.
