Earlier quoted context omitted.
I'd bet you a large sum of money this agency used Agile. Agile is not a guarantee of deliverables you care about. There is a lot of useless stuff you can deliver.
Well, waterfall used to not deliver anything at all. Not delivering anything is pretty useless.
That's pretty much untrue; had this project been a waterfall project then:
a) The devs would not have gotten paid until they hit particular milestones,
b) The deliverables would have been scoped upfront,
c) The agency would have eaten the cost of developing useless things, not the customer.
Because this was obviously an agile/Agile project:
a) The payment milestones were not specified upfront,
b) The devliverables remained unscoped until feedback was needed (which was well into the development phase),
c) The client eats the cost of developers time, whether or not milestones are hit.