I think the thing folk miss is when there’s an error like divide by zero, or the calculation would return NaN. I feel like this is the main gap/concern with using JSON and it seems to be rarely discussed.
Say what you want about NaN, but IEEE 754 is the facto way of dealing with floating points in computers and even if NaNs and Infs are a bit "fringe" it's unfortunate that the most popular serialization format can not represent these.