Author of the dishonest advertising here ;)
I don't think the fact that the tool introduces a mini language for crafting HTTP requests on the command line contradicts with the statement that the tool also provides what the author believes are sensible defaults (e.g., default to POST when sending data vs. GET when not, default to "prettifying" HTTP messages for human consumptions on the terminal vs. not touching them when the output is redirected, etc.).
"For humans" is meant to highlight the focus of this project on usability and interactive usage, as opposed to curl’s focus on feature-completeness across a number of protocols and non-interactive usage:
> curl is a tool to transfer data from or to a server, using one of the supported protocols (DICT, FILE, FTP, FTPS, GOPHER, HTTP, HTTPS, IMAP, IMAPS, LDAP, LDAPS, POP3, POP3S, RTMP, RTSP, SCP, SFTP, SMB, SMBS, SMTP, SMTPS, TELNET and TFTP). The command is designed to work without user interaction. [1]