True, but at the point when a competitor can say we sell the exact same product made in the same factory on the same lines. But we charge less, branding isn't as important. In fact your brand can work against you.
Who are they getting to do these blind tests? Coke, Pepsi, and RC cola have distinct flavors -- the generics do too, although I don't have enough experience to identify them. Cans, bottles, and fountains don't taste the same either. Branding and affinity certainly influence which vendor is preferred, but the drinks are not the same.
As someone who aced the Pepsi Challenge when they were around, they have very different tastes (I don't like the way Pepsi tastes at all), and I'm not the only one.
In fact, the Pepsi Challenge existed solely because Pepsi thought theirs tasted so differently.