Yes, the article is far from complete. But, your antecdote only goes to show your own bias towards women in science and engineering in general. By the time most females reach high school they have already been conditioned that girls aren't as good as boys in math and science. There's a far amount of studies showing this - at least in the US. As Monique said it is a very complex issue. Some of it starts at home and it starts extremely early. It's far more common for girls to be told they are pretty rather than smart. They have found some physiologic reasons that do influence math abilities - those with "math brains" tend to have higher levels of testosterone.
That all said, it still doesn't explain why the percentage of women active in the IETF is less than the percentage of women that are in the field. But it might have something to do with IETFers sharing your perspective that women just aren't interested.
Regards,
Mary.