While I see the benefit of this approach, I’m often baffled why people want to go either 100 % POSIX builtins or 100 % scripting language.

The biggest benefit of the shell is its clearly defined input and output (and error) interfaces. Most programming languages can read from and write to stdin, stdout, and stderr.

Why not use it and stick to KISS, replacing one cumbersome POSIX utility at a time, suites for the task? Then you don’t need to chain methods using less idiomatic code. But then you wouldn’t need these kind of libraries either.

I completely agree.

This is the approach that I took with murex. It comes with a stack of builtins for json, jsonlines, yaml, toml, csv, sqlite3, and others. So you have all the power of data types and intelligent management of structured data but also works with regular POSIX CLI commands without any additional boilerplate code when swapping between murex code and coreutils (et al). So one could say I’ve spent a fair amount of time studying this point you’ve raised :)

(Don't be afraid to self promote!)

One obvious benefit over what's suggested in the article is that you can use it interactively first, with autocomplete and such goodies, and transition smoothly to a script later.