Iterative development has existed since forever, since earlier than written history.

It is not something invented by the Agile proponents.

They have proposed a much more specific variant of iterative development, which at least as I have seen it implemented in any company which claimed to implement it, was really bad in comparison with the right ways of organizing development work, which I have seen elsewhere.

Any high quality product must be designed starting from a good written specification. Obviously, almost always the initial specification must pass through one or more update cycles, after experience is gathered through the implementation. This has always been universally used, not just by Agile practitioners.

There have always existed bad managers, who wrongly believed that a development process can always be linear and who did not include in their timelines the necessity for loops, but that was just bad management, so if Agile proponents pointed to such cases, those were just strawmen, not the best existing practices.