As an old hand in ICT it wasn't always like this. Something happened (in my opinion) between about 84 and 94 which systematically eroded and undermined women's experience in ICT.
I'd say it was gamer/pc culture but it's beyond that, although it's tied up in it. The conference cycles and tradeshows also played a role. Booth babes played a part, trivialising women's roles in public.
Several dozen highly significant design, analysis and operational roles in the internet vested in women back "then". People sometimes forget that. Women have always been a part of systems, networks, code. Always.
I'm not saying this was not an improvement, simply that it meshes with your timeline and sheds a different specturm of light on what you are pointing out. (to put it another way, there were traditionally many fewer women who wore pocket protectors and carried sliderules, but yes they were very much a part of the community)
you're pretty much on the money: https://www.npr.org/sections/money/2014/10/21/357629765/when...
The reasons speculated are much more boring, though. The personal computer was treated no differently than a Nintendo console, AKA a toy. So they (big coporate) simply decided boys were easier to market the home PC to (remember, this was decades before the general public took games seriously. People legitmately thought video games were a fad to die out of)
And that stuck. Snowballs into a time where the "nerd" stereotype more or less became the perogative term in the 80's/90's as a quick framing for some undesirable male. Every single piece of media had some stereotype of it, well into the 00's. It's not surprising women were put off. Men were put off too.
No particular mastermind here. Just corporate wanting to make a quick buck off of kids. Those kids just happened to pioneer an entire industry while Hollywood laughed at them.
Most people don't think women are incapable. In fact, they think women are far more capable and autonomous than the average commenter gives them credit for. That's why they willingly choose not to go into IT-related fields or tend to pick things adjacent to it, despite all of the things being done to pull them in. Let alone the fact many are willingly selling their bodies both as eye candy and physically, often without a mediator in between, despite a more stable and on average more lucrative job available to them. At the very least, many of them realized back then sleeping at your office working for peanuts to work on your dream project under supervision of some corporate bigwig wasn't nearly as great as whatever their other options were back in the day.
And god forbid we point out the elephant in the room: most people, women or men, aren't looking forward to working in an industry consisting primarily of the other sex. You take any profession and it will be an uphill battle starting from the cradle all the way to the grave. People acting surprised this hasn't changed immensely in 30 years are underselling the difficulty of solving the problem given all the other options available to any individual person today.