You can't explain something like that without considering the context, the social/work environment of those years, that led to this change. It may just have been that, for example, since the 80s new interesting fields were born or discovered by women, thus reducing their interest in computer science. This factor, for example, may have led to men predominance in the field, and that subsequently may have led to new scenarios/environments again, and so on till nowadays.
I'm sure that if there was a time when multitude of women were interested in CS probably today there would be more of them, and less men. That's unequivocal. Environments change, always in every field.
Your hypothesis has the convenient feature that it lets men off the hook, but given that the "social/work environment" is male-dominated, surely they have agency over it.
Rather than a "lack of interest", I offer alternative Wildly Made Up Explanations For Why Women Left Software Engineering In Droves and Had CS Enrollment Fall:
A) they may have been discouraged or prevented from studying a subject: Grace Hopper, for example, would have been an engineer but was prevented because she was a woman. Instead she studied math, as did many early female computer scientists. When Computer Science programs became common they may have hewed closer to the Engineering approach than Math, and when they became expected for programming jobs it may have closed off the pathway women had been taking into the field.
B) They may have faced harassment or hostile environments that discouraged them from pursuing a coding career. That is not them "being interested", it is "them being willing to tolerate the environment they were required to study or work in."
C) They may have faced discrimination in hiring, promotions, pay or been preferentially tracked into project management roles. You can't work in a profession if no one will hire you, and you can't advance if employers will only promote you into a non-technical role.
D) they may have faced impossible-to-reconcile expectations on their time, if they were unable to find employment working regular hours and so utilize child care. Men being willing to be a primary care giver is a relatively recent phenomenon.
I'm not saying any of these are true: I am saying that in the absence of any evidence my wildly made up speculations are just as likely to be true as yours. None of those things have to do with interest in technology, programming or working as a programmer. They all implicate the men who changed the social/work environment of computer science in ways that discouraged or excluded women. They are also all things that we could fix.
I'd rather focus on explanations that offer disprovable models we can use to fix the issues at hand if they turn out to be correct. Your approach is like looking at a crash report and being content with the explanation, "something obviously happened that was outside of expected parameters."
When I read the article, I want the next generation of girls and boys to have those moments of joy at technology. I don't want half of them to be turned off by the entirely-irrelevant social/work environment.
> I'd rather focus on explanations that offer disprovable models we can use to fix the issues at hand if they turn out to be correct.
So you are saying that you would fight one issue rather than another based not on arguments and evidence, but on the fact that the first can be fought and the other cannot (which is itself speculative)?
In my opinion this kind of reasoning has serious flaws. You could see already commenters on HN who say something like "Reading all these posts about sexism and women discrimination I don't want my daughter to work in IT". Doesn't that contradict to what we are fighting for - for bringing more women into IT industry? Doesn't it have to start with equal opportunity for children rather than fear (which in some - many - cases is wrongly induced?
I'm sure that if there was a time when multitude of women were interested in CS probably today there would be more of them, and less men. That's unequivocal. Environments change, always in every field.