[viraptor]

Many regulated industries.

Lots of developers using smaller embedded platforms.

Corpos with strict licensing requirements where it's less hassle to roll your own JSON parser than to file requests for library use to lawyers with justification (go through approval process for a single version of dependency (each version needs new approval)).

As you can expect the other extreme also has significant downsides...

[sushshshsh]

Hehehe... appreciate this answer. I wouldn't mind writing my own JSON parser because at least I can reason about how the code works, the only context I need is my language's syntax and not someone else's design assumptions :)