This tracks my experience with developer libraries. Most of them are very brittle abstractions.
It seems langchain and llamaindex are aiming to be the latter, and I'm building https://magentic.dev to be the former. I'd be interested to get your take on whether these abstractions would allow you stray from the narrow path while still being helpful!
Given the space moves so quickly, the frameworks always lack massively behind what they try to abstract.