Agile was definitelly taken in with the same irrationality as fashion at some point.

It's probably the best software development process philosophy for certain environments (for example: were there are fast changing requirements and easy access to end users) whilst being pretty shit for others (good luck trying to fit it at a proceess level when some software development is outsourced to independent teams or using for high performance systems design) and it eventually mostly came out of that fad period being used more for the right things (even if, often, less that properly) and less for the wrong things.

That said the Agile as fad phase was over a decade ago.