Lobsters doesn't have any contact information (I later learned they have an IRC channel) so I didn't get to hear an explanation from the Lobsters moderator until the topic came up here and ended up getting mediated in a Hacker News thread. The moderator was very clear that I was not only spamming myself, but I was encouraging my friends to spam too. For example, one thing I got specifically called out for was I invited my friend from the University of Tokyo to Lobsters so he could share his https://conwaylife.com/wiki/Lisp_in_Life project. This turned out to be very bad per Lobsters cultural norms.

The Lobsters moderator wants new people to earn their place in the community before doing anything that serves their personal interests. It matters not if your self-interests are aligned with giving the Lobsters community what they want. The moderator said they're a smaller platform where it's not difficult to influence the algorithm, and as a result he's very protective of that. You can't just play the upvote game. You have to make sure the mod knows you and likes you before doing that. Another thing I did was I used a loophole to help my friend share his project. In my culture, figuring out how to work around the rules without breaking them is considered a highly prized skill. When the Lobsters algorithm said his account was too new to post a link, I thought I was vouching for and reviewing his project link by posting it myself. But the Lobsters moderator took it as a personal insult and challenge to his authority.