What makes this “open” is - I presume - other trackers used to be tied to a forum with a registration, while this is supposedly not tied to a forum or a torrent

What makes this “open” is - I presume - other trackers used to be tied to a forum with a registration, while this is supposedly not tied to a forum or a torrent search website. However, from what I read some time ago, it’s actually connected to Pirate Bay, and when Pirate Bay used to be down, OpenBitTorrent was also down.