The vast majority of private trackers do not have a “hard” ratio economy like you describe. Most private trackers are flexible to give users ways to increase their own upload ratio without requiring that ratio to be “paid” by another user doing the downloading. e.g. when torrents are freeleech the users get to download for free but can still upload to improve their own ratio. And when there’s bonus systems in place those bonus points can be used to add to the user’s own uploaded data count. And sometimes private trackers have events where they make the entire tracker, or entire categories of torrents, freeleech so a whole ton of users get to download for free and will still be able to seed those same torrents afterwards.
does that mean that there are some users who will forever be below 1, and thus end up getting kicked out, thus resulting in the private tracker just… shrinking over time?
Sure, that could happen too. Private trackers will always get some users that just aren’t going to cut it and eventually lose access to the tracker. In most cases the tracker will just end up adding new users and maintain the total user count. Each tracker is going to be different in how they approach this… I think over time the user churn doesn’t happen as much, at some point there’s enough users on the tracker that are doing fine with ratio and whatnot while the tracker hits its own maximum user count so actually needing to replace users with new signups becomes less of a priority.
What exactly do you mean by super-seed? In torrent clients there is indeed something called super-seeding aka initial seeding but that does quite the opposite of “aggressively” seed anything. The whole point of super-seeding is to encourage other peers/leeches to share data amongst themselves and hopefully become seeds themselves. This results in your own torrent client avoiding uploading torrent data to the swarm more than necessary, it’s the opposite of building ratio if you’re minimizing uploading data.
https://en.wikipedia.org/wiki/Super-seeding
https://www.bittorrent.org/beps/bep_0016.html
It might be you meant to aggressively seed on an internet pipe with high upload bandwidth e.g. one of those 20 Gbps seedboxes or similar, that would make sense.