What does the term "camera-ready" mean and why is it used?

From the Wikipedia article entitled "Camera-ready":

The term camera-ready was first used in the photo offset printing process, where the final layout of a document was attached to a "mechanical" or "paste up". Then, a stat camera was used to photograph the mechanical, and the final offset printing plates were created from the camera's negative.

In this system, a final paste-up that needed no further changes or additions was ready to be photographed by the process camera and subsequently printed. This final document was camera-ready.

In recent years, the use of paste-ups has been steadily replaced by desktop publishing software, which allows users to create entire document layouts on the computer. In the meantime, many printers now use technology to take these digital files and create printing plates from them without use of a camera and negative. Despite this, the term camera-ready continues to be used to signify that a document is ready to be made into a printing plate.

Technology academics in particular tend to use it to refer to the 'post-print' version of the article (i.e. the accepted manuscript after peer review changes). But frankly, that is a misnomer; because in terms of the publication process, the term 'camera ready' doesn't relate to the peer review process. It is a technical term meaning 'ready-to-print', rather than a publishing term.

Having said that, in practice, the term 'camera ready' refers to a process of getting ready to print the publisher's proofs - which is a post-peer review stage (in between the post-print and the version of record). So in other words, if the academic has identified the document as 'camera ready' rather than 'post-print', then so long as the document doesn't have publisher's copyright on it then it can be treated as the post-print (if they haven't identified it as such).