There's a problem with any formalisation of patterns like Agile and other things like SOLID, Design Patterns (GoF) etc.: if you never saw the world before them, you will never appreciate why they exist.

Is anyone actually doing true waterfall development any more? How would that even work with the amount of open source software in use? The world is fundamentally different now than it was 25 years ago.

Stuff like SOLID and Design Patterns etc. are such good ideas that they've been incorporated directly into the design of modern languages and frameworks. It's natural that someone would pick up Design Patterns today and think it's all pointless. That's because the book was written in 1994 and it wasn't pointless to say it back then.

I guess this is why history tends to repeat itself. Many people can't internalise why something is bad unless they've experienced it themselves. Many more don't even read about it in the first place. Scary to think.