Indeed a lot of Agile ideas have proven to be too simplistic, and Agile is missing critical things. And in its original form, Agile is a failure.

But Agile contained important ideas. And if you read recent Agile authors, the "new" Agile is quite different. It is smart, nuanced, and mature. That is why we defined Agile 2 - to capture and knit together these new ideas, and also to fill some gaps.

Check it out: it is quite different from "old" Agile: https://agile2.net/