It may be easy to read and write, but few libraries implement it to the letter because the format doesn’t support extremely common use cases.

For those who disagree, try finding a json library that can reliably round-trip the data in a json file (i.e. ignoring spacing, tabs, and extra line breaks)

Common breaking points are discrimination between integers and doubles (e.g read 0.0 and write 0) and limits to the number of digits in a number.

It’s futile to try and change it now, but I think json would have been better if it had disjunct sets of integers and floats, did 64-bit ints (1) and IEEE doubles (1) as opposed to arbitrary length integers and floats, standardized serialization of time stamps and durations.

Requiring parsers to keep keys in file order also might have been a good thing.

(1) I know that opens a rat’s nest of users wanting unsigned 64-bit integers, signed 16-bit, 128-bit quad floats, etc, but I don’t see how not addressing that problem at all is better than picking reasonable values, event though that gives up on supporting those alternatives. Now, we have libraries making choices there, hopefullly in compatible ways.