[Falkon1313]

Personally, I like some of the ideas of JSON5, but it isn't compatible with JSON as implemented. Altering existing systems to use it isn't as trivial as you imply. And requires taking on new dependencies.

You'd have to rewrite anything using json_encode() and json_decode() in PHP, or the equivalent standard functions/methods in Python, C#, etc. And also take on another dependency. And maybe lose performance.

And then you sometimes may have to know whether you're dealing with JSON or JSON5, and what the program on the other end of the line produces or expects and can handle.

For new greenfield projects it might be worthwhile. But most of the world runs on legacy code and many prefer to stick to the standards and minimize dependencies. So it's not that simple.

That doesn't mean it's bad though. Like anything else in software, it's a trade-off.