Ah, yes fixing problems of one specific language at the protocol layer (and violating the spec). JSON isn't inherently limited to 2^52, JSON parsing in some languages and libraries are.

Arguably it's not some random language we are talking about, the JS in JSON means JavaScript after all ^^

Also the fact that there is no defined limit is more a bug of the spec that of implementations. In reality there is always a limit (at most the ram of involved computers) so not defining a specific max size is asking for trouble.