To put this into perspective, What.CD [0] was widely considered to be the music library of Alexandria, unparalleled in both its high quality standard and it's depth. What had in the ballpark of a few million torrents when it got raided and shut down. Anna's rip of Spotify includes roughly 186 million unique records. Granted, the tail end is a mixed bag of bot music and whatnot, but the scale is staggering. [0] https:…
I think what earned what.cd that title wasn't necessarily just the amount but the quality, as you mentioned, as well as the obscurity of a lot of the offered material. I remember finding an early EP of an unknown local band on there, and I live in the middle of nowhere in Europe. There were also quite a few really old and niche records on there which possibly couldn't be put on streaming services due to the ownership…
They also had good incentive structures for keeping the bar high -- you could get kicked out for having a bad ratio, so the easiest way to pump your upload up was to fulfil obscure requests for FLACs you could purchase online but were extremely difficult to purchase (if you're lucky it's just an unknown artist on Bandcamp). I discovered a lot of obscure music this way, some that I'm still looking for to this day after it shut down.
Because I cared so much about being part of that private tracker, this is what also prompted me to rent a seedbox for the first time. I paid in Bitcoin out of paranoia (I lived in Germany where the fines for piracy are HEFTY, and they actually do come after you) back when Bitcoin wasn't really worth that much, and later found that that old wallet suddenly had a couple thousand in it instead of the spare change I couldn't move!