When you know your position, you can say “no.” When you don’t know, you say “yes” out of fear. You build a feature because you’re afraid of what will happen if you don’t. That’s not a strong place to be competitively and it’s not a coherent place to be in terms of your product design.
It’s easy to look confident when you know what you’re talking about. (And to be clear, you should know what you’re talking about most of the time.) But on that rare occasion that you don’t, letting people know that you’re confident enough to admit that you’re at a loss is when you beat the level boss. No one has all the answers, and pretending you do doesn’t make you look confident, it makes you look a fool.