A bunch of folks bloviating why it's a terrible idea and no one will use it. Meanwhile it's become extremely popular. And you're conclusion is they're "right on the money?" Um, OK.
What's your definition of "extremely popular"?
I believe SQLite "uses" json5 in the sense that one of its important customers asked for json5 ingestion, and json5 was supported only for input in the spirit of the robustness principle.
From the horse's mouth.
"The important point to keep in mind is that SQLite will read JSON5, but it never writes it. The JSON that SQLite generates is canonical JSON that is fully compliant with the original JSON spec."
https://news.ycombinator.com/item?id=35962213
If your definition of success is accepting an extension because an important customer asked for an extension, so be it.
In the meantime, are you sure you want to compare plain old JSON with the mess that's JSON5? Because projects such as SQLite explicitly refuse to support JSON5, and apparently their decisions pass off as the definition of success.
> and millions of downloads
Are you sure you want to use that as a success metric?