What's so insane about it? I ask as I've recently been working with curl for webdav backup scripts and haven't had too many problems beyond fat fingers.
it's modeled after Netscape 2.0's view of the web, and not after how HTTP actually works.
It tries to force different protocols like HTTP and FTP into a single API, making for lots of combinations of switches that sometimes do and sometimes do not work together.
I could go on, but it's all stuff like this. It's not a bad API, just very archaic.