But the same can be said about waterfall, every buzzword process have one success story and that one story will then be used to invalidate every failure, which is not really an useful way to look at it.

The problem is that by now more people have failed at agile then succeeded and instead of going back and modifying or challenging the universality of agile they way it happened with waterfall, people keep doubling down on the universality of "The Agile Manifesto" by discounting any failure as "no true agile".