Everyone else's comments are pretty spot-on, but I will add this tidbit.
I give every team the chance to prove themselves. Just like Photoshop - you can get the same thing done in a million different ways - and it's not about the tools you use, but how you use them.
However, having said that...
If I see that Agile methodology is being tarnished with constant interrupts and blockers (by a rather traditional stockholder and product owner, "scrumbag"), it's time to go waterfall. A-Z. Otherwise, your full product will never see the light of day, and in my experience, it will be using things that are nearing or have reached EoL.