What Kind of Role Does User Research Play in Product Building?

The act of engaging with user research, perhaps like live observing something watching a user struggle becomes kind of like a uniting, a focusing force. The next level is to think like, well, we know from a research perspective that just asking everyone any question for all the time is not going to help us out. And then it seems like there's a next level above that, right, which is, okay, they're in touch with the customers, but are we using the right representative sample of customers? Are we using the appropriate techniques relevant to the product challenge at hand?