Also need to appreciate the immense cost of splintering off yet another data format. The value of common formats is that even if it's not ideal for any of our individual needs, we're at least all using and maintaining the same tools.
I think where experiments like this shine is when you're doing some limited scope personal project. Like I'll probably use this for a few days of Advent of Code to see what ideas stick.
We started hand editing a lot and making more mistakes, but we have a lot of code generated json from build pipelines and use json with a number of different libraries in different tools already so didn’t really want to switch to yaml or toml.
Jsn is not meant to replace json, we are still using json a lot natively, we just can write config files more easily and jsn spits out fully compliant json for you, or you can use a python dict the same as json.
Jsn does not have a serializer, once it has been parsed it is json.
If people didn't tinker and experiment and introduce their ideas into the wild, we would basically never make progress.
I suspect there's a time and place to use new experiments. Production isn't usually it.