A Hacker News discussion revisits XML's technical merits, arguing its decline wasn't due to inadequacy but the dominance of JavaScript and browser convenience. The post contends that XML Schema Definition (XSD) and namespaces provided built-in validation and composition that JSON lacks, making it a more rigorous choice for machine-to-machine communication.

The author frames JSON's rise as a victory for developer convenience over correctness. While JSON is simpler to parse in browsers, it offers no native schema validation, forcing reliance on external tools like JSON Schema. This trade-off sacrificed formal rigor for immediate pragmatism, leading to widespread issues with data integrity and type safety.

The critique extends to the industry's pattern of retrofitting inadequate technologies. Just as the JVM required massive optimization to become viable, developers have spent years building validation libraries and type systems (like TypeScript) to compensate for JSON's shortcomings. The argument suggests we prioritized aesthetic preferences for minimalism over engineered solutions.

Looking ahead, the discussion questions whether the pendulum might swing back. As systems grow more complex, the need for robust data contracts is resurfacing. Tools like Protocol Buffers and Avro echo XML's schema-first approach, indicating a renewed appreciation for formal specifications in distributed architectures.