In most cases where I want to do some validation on JSON I find that I usually have a class/struct/object that represents the payload and I want to unpack JSON into it (or dump that class to JSON). Ultimately, there are already nice tools to do this (eg; marshmallow on the python side). So unless I'm crossing language boundaries writing a separate jsonschema and using that is more work and I have to keep it up to date.
And in the cases where I want to cross language boundaries at this point there's less and less of a compelling case to go with JSON and not eg; flatbuffers/protobuf/thrift/capnproto since you're writing a schema anyways.
In most cases where I want to do some validation on JSON I find that I usually have a class/struct/object that represents the payload and I want to unpack JSON into it (or dump that class to JSON). Ultimately, there are already nice tools to do this (eg; marshmallow on the python side). So unless I'm crossing language boundaries writing a separate jsonschema and using that is more work and I have to keep it up to date.
And in the cases where I want to cross language boundaries at this point there's less and less of a compelling case to go with JSON and not eg; flatbuffers/protobuf/thrift/capnproto since you're writing a schema anyways.