What makes a social network “work”?

Typically, we say that a social networking service works when it achieves some of these:

• Community – gives users the ability to create communities they can feel a sense of belonging to.
• Freedom of expression – expands people’s ability to speak their mind in a … umm… meaningful way ? (looking at 4chan’s /pol/).
• Rich expression – actually offers tools to express yourself (presence of features like markup, formatting, embeds).
• Constructive culture – becomes an environment where people learn and participate in constructive and fun activities — like university clubs. (Sorry for the example, but Reddit’s r/anime comes to mind.)
• Privacy & safety – respects users’ privacy and safety.
• Developer support – provides good developer tools.
  • Example: In Numbers: The Best Anime of the Decade from MyAnimeList — a huge data-driven article made possible by open tools and APIs. (also a huge web page, might take forever to load all figures)

Feel free to add more points, or challenge the ones I’ve listed.

It seems like a general consensus here on Lemmy that — no matter how many times you try — Reddit will always slip from Aaron Swartz to u/spez.
Why do you think that is?

Disclaimer: I wrote the post by myself, but used AI to refine my bad English and markdown,