Sure, validation is not a silver bullet. However, lots of startups make it or break due to luck and no-one(yet) can't eliminate randomness in a stochastic(debatable) system like technology entrepreneurship ecosystem. Validation helps to decrease the chance of failing, though. The famous quote by George Box reads "Remember that all models are wrong; the practical question is how wrong do they have to be to not be useful."
Also validation is not listening to what people tell, it's also observing actions of users when they interact with the MVP.