[ergothus]

> if you can't explain the earlier oscillation, why should I accept the later oscillation

Clearly women in the 1970s had no other obstacles - they couldn't obtain credit(!), much less be on equal footing in so many other ways. The issue is not "but there is an earlier oscillation", it's "if women have been slowly moving in direction of equality, what reversed that?" or "If women were able to 'be interested' back then, how can we claim they aren't now"?

[XorNot]

Women started being excluded once computing was considered a "serious" career path and salaries ticked up. Before then serious engineering was mechanical engineering, chemistry, physics.

Sexist (and racial) exclusionary behavior ticks up once a field becomes commoditized and the general populace move on in, because the general populace carry with them the prevailing attitudes of the times.