I think this is a general cultural phenomenon not specific to the sciences- people are told they need to be aggressively confident to be taken seriously. Even as a kid parents and teachers will suggest to kids to edit words expressing uncertainty out of their writing. They are coached to talk like that when public speaking, at job interviews, and even dating.
As a scientist- I also think papers and grant applications are more likely to be accepted if they use an irrationally overconfident tone, at least in the abstract and introduction.
As a scientist- I also think papers and grant applications are more likely to be accepted if they use an irrationally overconfident tone, at least in the abstract and introduction.