Without an explicit end delimiter I can't tell if I have all the records in the data. Looking for an EOF kind of works locally but not in HTTP requests. Firing data around the web is not reliable. JSON has the massive advantage that if you don't have all the data, including that closing curly bracket, it won't parse correctly. This format doesn't have that. Consequently I can't use it.

If you want JSON-but-with-<missing feature> there's always https://json5.org/.