It seems like part of what you’re responding to is false humility (“I have no idea what I’m doing”), when what we need is just humility (“I’m really good at _____, and I’m trying to get better at ____”). In other words, honesty with oneself and honesty with others about oneself. I can relate to that feeling of wanting to make sure people trust my expertise and understand how I can contribute, but not wanting to come off as one of those designers with the big ego. Combined with the ever-changing nature of the design profession, I wonder if that’s why we downplay ourselves like you’re describing.