Much of this has to do with scale. In small communities, interactions are more likely to skew positive, meaningful, and desired. The discussions that rise to the top are those that are most interesting and relevant to the community.
In giga-networks like Twitter, you might get some vague sense of a belonged-to community, but the boundaries are fuzzy at best and when posts find their way beyond those boundaries, context is lost and you end up with scores of randos whose full-time job is seemingly to surf the service searching for posts to clout farm with by either replying to them with their entirely uninformed (often inflammatory) opinion or quote-tweet with similarly uninformed ridicule, which can turn disastrous for the quoted poster if it goes viral. The posts that rise to the top are the ones that are the most flame-baity and controversial. It's a much more negative experience overall.
Scale and boundaries yes. A community is participative. If everyone is just passing through, the community can't feel familiar and it can't self-police its vibe.
In giga-networks like Twitter, you might get some vague sense of a belonged-to community, but the boundaries are fuzzy at best and when posts find their way beyond those boundaries, context is lost and you end up with scores of randos whose full-time job is seemingly to surf the service searching for posts to clout farm with by either replying to them with their entirely uninformed (often inflammatory) opinion or quote-tweet with similarly uninformed ridicule, which can turn disastrous for the quoted poster if it goes viral. The posts that rise to the top are the ones that are the most flame-baity and controversial. It's a much more negative experience overall.