Probably most of us reason from stereotypes a lot of the time. I'm ashamed to admit I've recommended not hiring a guy I interviewed for a sysadmin job basically because he showed up wearing a suit and tie.
I was once told in an interview for a statistician role that the questions were designed for male candidates and I shouldn't worry if I struggle with them. And this was a big FTSE 100 company.
So I would show up to job interviews in a basic black suit, and I liked the way I felt when I wore it. The old-school attitude about "Dress for Success" is just one more thing that's become retro and ironic these days.