Isn't that a limitation of the language and API rather than the parser/decoder? I would guess that most users don't want a JSON decoder that depends on some library for arbitrary-precision numbers and returns such numbers for the user's inconvenience.

The summary table suggests that a real bug was found in about half of the parsers tested, and even a few of those bugs belong to a category that one might choose to ignore: almost any non-trivial function can be made to run out of memory, and lots of functions will crash ungracefully when that happens, rather than correctly free all the memory that was allocated and return an error code, which the caller probably doesn't handle correctly in any case because this case was never tested.