> just a group of people who knew each other and shared stuff.
I wish! The thing is, private trackers are not like that, at least not anymore. It's more like a bunch of people trying to show who has the biggest e-penis (ratio, highest upload, etc.); and they're definitely not "friends" or know each other. I was heavily involved in the PT scene for a while 15 years ago, and really hated how big the egos and how many the dramas were there. Now I just lurk.
To me, the best way, or the "spirit", is that you either share it with your friends only (which is what I typically do nowadays if I buy the stuff myself), or just publish it publicly (ideally anonymously), than only to some condescending pricks which somehow think being able to download "exclusive" content others share is a bragging right.
FWIW, this is basically how eMule and most Japanese P2P softwares worked, so it influenced me a lot. There is zero gatekeeping; once you share, the files are no longer "yours". People can't even tell who published them.
But again, that's just my value, and I keep it to myself. I totally see how this is not enough incentive for others to "share" their stuff.