I think the point of those situations is to make sure they're not under the impression they're alone in domains where, if you don't do specific programs, girls often think they are. Essentially, you create a social support net that may not otherwise be there.

In my view, you're technically right. We shouldn't have to emphasize one side over the other. The problem is we're combating an existing, underlying emphasis. If a balance scale is unbalanced towards one side, you don't balance it out by adding weight to both sides. You have to add weight to the one side until you've restored balance.

Now, I think it's fair to question how much we should segregate and isolate with respect to that. What you describe as happening in middle school is probably not the best approach. I think it would probably make more sense to open a whole class, gender-unspecific, but, again to create that social support, perhaps try to group the girls in the class into one of the sections (assuming there are multiple ones). The problem is, in that case, probably a marketing one. Presenting it as an girls only course may increase the mystery and interest, and, thus, enrollment.