If that is true, and I'm not sure it is, it could only be assessed as sexism, which includes the absence of women in positions that encourage those statements.
Student or Learner
I sometimes hear or see such expressions as "a man of dignity", "a man of intergrity", or "a man of action".
When you refer to a woman with such qualitities, do you say "a woman of dignity", "a woman of, intergrity", or "a woman of action"?
In my impression, "a man of..." is much more common. Can you guess the reason that "man" is much more frequently used?
It's also possible that men are simply written about more. At least historically.
One could also argue that virtues such as integrity and dignity are expected/presumed of women. Having to say that a lady has integrity is to entertain the idea that her integrity was in question.