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: https://text.npr.org/
Or https://tildes.net/ compared to Reddit.
NexusMods is a private company with their own conditions for using their services.
You are not entitled to anything on others’ properties, including your ability to speak.
There is no freedom of speech here on lemmy.world either for you, they can restrict and block your posts from being seen by others, still their rights to do so.