We had this problem with JSON in the first few years. Various ad-hoc JSON parsers that are not in fact compliant parsers, but mix-in various JSON-like features

We had this problem with JSON in the first few years. Various ad-hoc JSON parsers that are not in fact compliant parsers, but mix-in various JSON-like features in the syntax and have specific expectations about formatting. The reason JSON got past this stage is that the JSON spec is sufficiently simple that when a popular JSON parser for every platform/language got established, people just used it. XML on the other hand is a nightmare of complexity and it even had the occasional remote code execution vulnerabilities in some parsers (they're that complex). Which means many applications would "handroll" something that amounts to a child's interpretation of what XML is and expect that. Truly unfortunate. I wonder if SOAP based on JSON would be more successful. Probably yes. But we didn't have it back then. KISS