[ryukafalz]

Some torrents depend on trackers, yes. Others use magnet links, which aren't dependent on trackers at all. The data typically served by a tracker is instead stored in the DHT:

https://en.wikipedia.org/wiki/Mainline_DHT

[ComodoHacker]

DHT helps with downloading, but content discovery depends on tracker. You can't search for, rate or review content in DHT.

[erikpukinskis]

Content discovery can happen over any number of decentralized channels including email, diaspora, etc.