They're not plain text, they're a text encoded structured file format. And the file format is stable. A stable file format is the most important difference her

They're not plain text, they're a text encoded structured file format. And the file format is stable. A stable file format is the most important difference here, but the text encoding means that small incompatibilities can be solved by a human rather than needing to rely on an upstream maintainer to recognize and explicitly handle your unique situation.