The kind of folks who are going to follow through with this sort of advice in the first place are likely to be more conscientious than average, not less.

Being better than average doesn't mean that it's useless to improve on it.

such folks may be better off developing other skills, which are also valuable in other contexts

Developing conscientiousness usually doesn't stand in the way of developing other skills.

Saying that you should "impress women" strikes me as the kind of truism that's common in bad dating advice.

I didn't. Most heterosexual guys already spent energy on "impressing women", my recommendation is about challenging that energy productively.

Adding two woman to a group of ten males, the behavior of that group changes. They suddenly optimize more for the image they are projecting.