There is a resentment to being told you're judged on confidence. First of all, what kind of way is that to judge someone, assuming you're even judging at all? We all know that everyone has flaws and insecurities and things they struggle with; why is knowing and feeling this about yourself in a particular moment derogatory? Couldn't it simply be more aware or more honest or both, rather than worse? And second, if you're judging others on confidence - if that's really what you're doing - why are you proud of it? It seems as if you're using someone's current feeling about themselves as a cheat sheet instead of using your own intelligence. And third, if you think the method makes sense, then why are you suggesting that someone falsify it? Either confidence is an honest measurement and we should respect people who are honestly and openly low or high on it, or it's everyone's responsibility to show a brave face because ya gotta; is there a good argument that it can be both?
It's a bit like telling the kids who come in for a test, "Now, class, you will be judged on whether what you write down matches what's in my key. If you don't know the right answers, copy from your neighbor!" We use this metric of confidence - we believe - to measure something important. And then we tell people it's their responsibility to falsify the metric - or talk themselves into feeling it - or in the example, copy their neighbor's already confidently written answers - so that everything can go as planned.
It means something or it doesn't. And what it means is relevant or it isn't.
There are people who will say, "Look, this system you're using seems absurd to me, and you can't explain how it makes sense. You aren't even trying. I will not participate." And then those people, for not falsifying their metrics (in other words, not going out of their way to feel and present as confident), and not participating in what seems absurd, will be interpreted as hopeless. Diffidence is insecure is weak is pathetic is no good. But they could have falsified and puffed up and played the game like anyone else. They just found the proposition distasteful, and they refused.