Running with the json example you don't need a json library in lisp because you'd just dump an s-expression holding the data you want directly. You don't need a library to parse it because it's already in a format that lisp can understand.

Hilariously enough the project that made me switch to lisp from python as my scripting language was writing a lightweight parser for ascii delimited files - https://en.wikipedia.org/wiki/Delimiter?useskin=vector#ASCII... - instead of csv files. After doing it in both I had the eureka moment of using nested s-expressions in the scheme version instead of special characters. All of a sudden I had access to a csv like file which could be arbitrarily nested and didn't require me to worry about escaping. The next mind blowing moment was when I realized I could embed the code of the parser as the header of the format as the type definition and use it to evaluate the format with the program that was used to create it.

You don't even need some deep insanity to do it just:

    (eval `(,(car ls) (cadr ls)) (interaction-environment))

It also shows why I wouldn't use lisp for everything: if I wanted to ingest a file of a known csv dialect that won't fit in memory I'd do it in C after doing the prototype/master version in lisp. I also wouldn't trust running unverified source code from the internet. But for internal projects it's better than sliced bread.