Shell programming is high density inter-language glue. You simply have more options of implementations to call out to and so less to write.

I can trivially combine a tool written in rust with one written in js/java/C/whatever without writing bindings

If you want a better guess: It's because of the man pages for all the tools are likely duplicated across so many media for the LLM training that there's just an efficient pipeline. They go back to the 70s or whatever.

So, mostly re-enforcement along multiple vectors.

I'm not convinced. I don't want to rack servers and diagnose bad RAM like it's still the 90's, so I'm paying someone else for the privilege, especially to get POPs closer to customers than I want to drive or fly to setup, especially in foreign countries where I don't speak the language or know the culture. Fun for vacation but a recipe to waste time and money setting up a local corporate entity and a whole team when I can just pay GCP or AWS and have a server on the other side of the planet from me faster than I can book a plane flight and hotel reservation there.

There's also the maintenance of the server to be considered. Vercel or other PaaS/Lambda/GCP functions/etc serverless means there's just less crap for me to manage, because they're dealing with it, and yeah, they charge money for that service. Being able to tell Claude code, I setup ssh keys and sudo no password for you, go fix my shit; like, that works, but then the hard drive is full so I have to up size the VPS, and if you're stupid/brave, you can give Claude Code MCP access to Chrome so it can click the buttons in Hetzner to upsize for you, but that's time and tokens spent not working on the product so at the end of the day I think Vercel is gonna be fine. AI generating code means there are many many more people trying out making some sort of Internet company, but they'll only discover cheaper options only after paying for Vercel becomes painful.