Ever tried Agile development of a software library or of infrastructural systems? Stuff that needs to be thought out before publishing? Where experience counts? Where you don't have a team of 10 people dedicated to sprints of two weeks? Where produced software actually has to be maintained? In short, where you have a small shop that needs to make a difference.
Yes on all counts. At the same time.
I ran the dev team, already had experience of very early agile predecessors (DSDM), I was told to "do" agile with my team and went into it as a confirmed sceptic trying hard to keep an open mind, and f*** me it worked. Well. Really well. Several people (inc me) thought we couldn't do product development agile, couldn't do support and maintenance agile, couldn't support pre-sales agile, well we did, and it worked better than anything else we did in a whole lot of ways.
I have also since seen the same agile process (SCRUM) used so badly it drowned a project in treacle, it would have been hilarious if it wasn't for the amount of money you were watching being pissed up against a wall.
Agile is a tool, it is a better lathe, used properly it can produce things of great beauty and precision, but it is still just a better lathe - if you are trying to use it to drill a hole or cut a straight line you will still fail, if you leave the chuck key in you will still get hit in the nuts (if you're lucky) when you start it. Know your tools.