If I could add to what BuckeyeTexan said: that sets up the possibility of much more effective and efficient processes. I used to feel sorry for Q&A people sometimes - when they’d get thrown a large complex system all and once and were told to start testing. HEY! You’re holding up delivery! It was the same attitude that the engineers had faced, but much later in the process when managers had already spent a lot of money and were already under pressure from customers to deliver.
Like BuckeyeTexan said, the agile approach gets everyone involved from the start, in their respective roles and allows taking it a bit at a time. While doing that, you don’t need to rely entirely on generalists who feel uncomfortable about taking on certain tasks - especially under pressure to complete them. You can have various specialists forming a nice balanced production line of sorts. And the best thing about it - it goes on and on. I don’t mean that it delays project indefinitely. I mean that people can get expert in their specialty work, get in tune to working with everyone else in their group - and even continue the same way on more than one project - acting more as a continuous production entity than an ad hoc group with too few resources and time.
The other issues I have with Agile is that I do work mostly on large complex system, other groups may be running waterfall, and others XP, they all change delivery schedules on the fly and it is very difficult to pull it all together for a clean delivery. That's why I often have to be the project manager as well as the QA manager, most teams do not like to watch the other’s ball, and the PMO’s tend to vastly underestimate the complexity of the project as a whole.