Not only that... when you test the efficacy of medical interventions the gold standard to strive for[1] is not whether the new intervention is better than placebo, it's whether it's better than $CURRENT_BEST_KNOWN_INTERVENTION. I suggest we should be aiming for a similar standard in testing software engineering methodology.

I think it would be very hard to argue that Waterfall ~= $CURRENT_BEST_KNOWN_METHODOLOGY.

[1] Of course, this isn't usually what happens in practice when pharmaceutical companies are doing their own testing, but it's what should happen if you actually care about efficacy and not just PR/sales.