It is a good library API with good support for async and that sort of thing. As a user it is less work to integrate the Nth protocol in a library I understand than to read the docs and try to reverse engineer some new API model of how to do things including asynchronous and configurations and TLS/cert management etc. there are a thousand ways to skin the cat, and libcurl is a good one. I want to learn a bunch of new distributed protocols because those are real things; I don’t want to learn a bunch of different APIs to do the same things because those are arbitrary wrappings to the real thing. If an API is successful enough it would be real, but cleverness in API design isn’t that useful without the popularity.