As Lauret explained, common consistency is "being consistent with the world." This means our API should conform to well-established and/or authoritative standards; or if none are available, to the community consensus.
If an API is not consistent with the world, it forces developers to learn a new way of thinking. This may require a sizable time investment, which may deter the user from trying the API in the first place. Therefore, having common consistency will likely improve developer experience, and may even drive up the API's adoption rate.
For an HTTP API, the obvious standard to adopt is the HTTP/1.1 specification. This is a standard sanctioned by the World Wide Web Consortium (W3C), the authoritative international ...
