By raw bulk most JSON is not written by humans, it is an interchange format. Yes of course a human is going to write JSON in snapshot tests. And it is for sure a feature that it is easily written by humans.
Notice I did not mention readability. JSON was always meant to be human-readable; and its popularity is a testament to the rapid turnaround on debugging that the readable aspect of JSON affords. This is, say, in contrast to BSON which is similar but not humanly readable, and unsurprisingly less popular despite its bandwidth advantages.
Config formats are, by raw bulk, generated by humans, and need to be readable (ideally reproducibly across implementations) by computers.
Notice I did not mention readability. JSON was always meant to be human-readable; and its popularity is a testament to the rapid turnaround on debugging that the readable aspect of JSON affords. This is, say, in contrast to BSON which is similar but not humanly readable, and unsurprisingly less popular despite its bandwidth advantages.
Config formats are, by raw bulk, generated by humans, and need to be readable (ideally reproducibly across implementations) by computers.