Why would a hype protocol use outdated concepts instead of the hype JSON?

Wouldn't medical records actually be better in JSON, because the field could expressly have "kg" or "lb" suffix within the value of the field itself, or even in the name of the field, like "weight-in-kg" or "weight-in-lb"? This is actually the beauty of JSON compared other formats where these things may end up being just a unitless integer.

The biggest problem with medical data would probably remain the human factor, where regardless of the format used by the machines and by MCP, the underlying data may already be incorrect or not coded properly, so, if anything, AI would likely have a better chance of interpreting the data correctly than the API provider blindly mislabelling unitless data.