I guess I don't understand the point. Could someone summarize why I would use this rather than writing my utilities in something that doesn't compile to a quirky, limited programming language?
Because the runtime for those utilities is available on just about every Linuxy OS there is. Saves you having to install the runtime separately, eg in your CI pipeline.
It's not, really. The claim would be that it's portable, but bash can be a little finicky in that respect.
The documentation didn't mention what version of bash is required, but it'll be something. And plenty of systems will have old versions of bash - especially once you move out of the world of "my laptop" - obviously.
As has been mentioned elsewhere, it makes many times more sense to just learn bash, than to learn this. You likely already know some, and it excels at the jobs it's designed for - which is chiefly to launch processes and pipe output around. Subshells are elegant, even if making sure everything launched by your script is 100% finished before you exit can be a pain.