The earlier you go, the easier it is to pinpoint a single demographic (although not sure what's the point in doing that). But from '95 on, I'd say it's pretty misleading to point that to US or middle class engineers. Even in 95, it was already available to non-ranked university students in peripheric countries, and not just for those studying at engineering faculties. Although most web content at that time was related to porn (90%) and jokes (9%) and some other content (1% - probably stem and engineering?), but I don't know exactly in what philosophy that content is considered prominent and default. From 2000, it was accessible and even not too expensive for most middle class households by landline. From that time on, it was more about which demographic is not yet present... I think you had to wait e.g., another 10-12 years for mobile-first minors and for the idle retired people.