The UX is important. It's important that all users have the same one. For link aggregators, you want comments displayed as a tree. For microblogging, flat lists work better, especially when people post "threads", which they do.
> What does this mean? Every other platform you mentioned are social networks.
I meant a Facebook-style social network.
That's subjective and exactly the type of thing that could be handled in a client. In both cases you're displaying the exact same data. A microblogging thread may be displayed as a flat list, but it's still a tree like a link aggregator thread.
> I meant a Facebook-style social network. So a platform to post what are essentially blog posts. In ActivityPub, that would be the Article type, which, according to the spec, has no semantic difference from Note. An Article could be created as a Note and vice versa with no semantic difference or loss of data. Just like above, the data is the same and the only distinction is the visual presentation of it.
There needs to be a web UI of some sort. You need to be able to send people links to things that they can open in their browser with nothing extra installed. It's a hard requirement. You can't require the use of a client app.
Why not? it's text; you could make the same exact post on reddit and twitter (barring the length, which could be truncated in a federated context). Link aggregation is basically just microblogging with the extra constraint that the initial post has to have a link.
> Smithereen is a social network
What does this mean? Every other platform you mentioned are social networks. On all of these platforms, a user posts text or media posts. Displaying them in a different UI doesn't make them radically different.