>This was a deliberate design decision in most private tracker software, notably Gazelle, because it was accepted that people would post the .torrent files in other places

Err no. Passkeys were designed so that you could track users without needing IP address -- IP tracking is fragile and doesn't work with multiple peers/ip, which happens very frequency.

> Many trackers also limit the IP addresses that are permitted to join a swarm based upon the same identifier in the torrent file

Once again, not really. Most sites don't really care what IPs you use (so long as they aren't part of blanket banned regions or similar). PTP does not require you disclose your IP, they don't care if you use multiple IPs, and doing so will not flag you for a ban. There are better ways of finding bad users, which includes sharing between trackers.

>(a) that person would likely get banned from ptp, (b) it probably wouldn't work in the first place because joker's servers couldn't join the swarm and (c) the information that the owner of joker can glean from such a torrent file would be almost entirely useless unless the goal is boosting the ratio of the user.

A) No, they wouldn't.

B) Unless joker.com is using a custom bittorrent app (highly unlikely) they can join the swarm just fine