The one thing agile helped here is to take that process and make it fast.

The problem with "Requirements, prototype, feedback, iterate, qa, qa, qa, release" is that most large shops turn that into a 3 year process. As in, a group sits in a room for 6 months and writes some insane "Requirements Doc". Then six months of prototyping against it before any customer has seen anything. Etc etc down the line until you're a programmer looking at a 3 year old requirements doc with a thousand questions that arise during implementation but the designers who wrote the doc left the company two years ago, etc etc

Waterfall was to me inarguably worse than agile.

At least with agile people try to do requirements, prototyping and iterating in a very short period of time, so the feedback loop with customers actually works, and you actually release something on a regular basis.