The main problem for json is that it doesn't support comments at all. So it's completely unsuitable for config files of any length, as you can't leave notes behind about what the different options are. Either that, or all your config names are ridiculously long in order to get across the meaning and formatting and usage, like...
{
"email_receiver_list_for_twice_monthly_billing_report_semicolon_separated": "[email protected];[email protected]"
}