It is not entirely data farming, a lot of this is due to use of heavy assets like fonts, frameworks, images, videos, etc. A lot of that is downloaded as part of loading the site initially and then the browser has to render/compute the site’s use of JavaScript, CSS, etc.

Fonts and some JS assets are cached by the browsers and CDN to try to minimize redownloading it but it doesn’t change the fact that average websites today are much heavier than it was back in 90s.

See how fast this site loads: text.npr.org

Or tildes.net compared to Reddit.