Even the brief bloom of the torrent and sharing scene was incredible, though. Scarce works that circulate manually are in near-constant jeopardy, because every new copy takes new effort. But a whole lot of unique content, from jam-band tapes to obscure translated books, just showed up on torrent sites and got shared widely. Even if it's inaccessible at the moment, that stretch may have spawned enough copies to endure across the next few transitions.
Eh, I feel like we've almost fully gotten away from bit-rot. Bit-rot was a problem because individuals don't bother to go to the effort of constant IT administration, and don't have the economies of scale required to afford good data redundancy.
But individuals don't have to back things up "personally" any more. With one command, I can send three copies of any file to three object-storage providers. Each one (according to the Dynamo architecture, which they mostly all implement) is holding 17 copies of the data on 17 shards, and replaces copies from the good ones whenever they go bad. Each provider's copies only exist in one region, but the region is different for each provider selected. As individual object-storage providers die, I can find new ones and sync my data over from the surviving ones. As long as "cloud [redundant] object storage" as a concept exists, I won't have to do much at all to ensure continued integrity of my data. All the details—including porting my data to new physical substrates when old formats die—are being handled under the abstraction, and converted into (tiny!) monthly fees that are lower than what even a zero-redundancy tape library would cost me.
And, of course, the data I'm sending is encrypted, and not even with a symmetric key, but rather a PKI key where the decryption half of the key is held in cold storage (i.e. in hardcopy base64 in a safety deposit box at a bank; and a few other places.) If I'm uploading rips of something copyrighted, nobody will ever know that but me. I'll be able to get the data back out when the time comes to dust it off and share it.
The masters still exist, I'm told, but that's no good to anyone - they won't be re-released because it would require too much intellectual property wrangling and nobody cares enough to bother, and sooner or later that hard drive will die and that will be that.
Edit: Wait. Am I part of the problem?
If you want more, look either of them up.
Meanwhile, a lot of unique live-concert recordings (often made with the band's permission, unlike the Salinger tapes) vanished with the demise of What.CD. Presumably some people still have them, if bit rot hasn't caught up, but they simply ceased to be available.
I'm not sure these ever landed on torrent sites, but the first album from Godspeed You! Black Emperor is considered lost, and Eminem's debut EP was unavailable for more than a decade. Both are (early-)digital-era works, which raises interesting questions about the fragility of even modern content. The archive-less disappearance of quite a few online short stories, flash games, and Soundcloud tracks makes me suspect that in a few decades, quite a few more "first works" of notable creators will be unavailable.
Years ago, I was on a university private tracker. It was used more to share hard-to-find resources than for any actual piracy, much less piracy of anything new or policed. (I'm sure people stole plenty of 50-year-old textbook PDFs.) But when the hoster shut it down abruptly, everything simply vanished, including all kinds of hand-scanned and annotated stuff which may be literally irreplaceable.
Meanwhile, something like Kickass Torrents can be shut down and abandoned by the owners, but the content all reappears almost immediately. The private-tracker model has lots of advantages for community building, but as far as robustness it undermines the entire concept of P2P sharing.
It's sort of funny to see that even something released post-internet can float in and out of availability like that. I generally class recent content as "lost" or "available", but obviously there's still a third category.
Yes, I just noticed I accidentally dropped the "of thousands" part while writing my comments.
This should be a golden age for information preservation. Instead it's a dark age. I personally know several eye-wateringly good bands whose catalogs are not available anywhere, at all.