Popularity has absolutely nothing to do with centralized search sites. Nothing technical ever prevented "ed2k-based Pirate Bays" to take off the same way, it's just that eMule included search so sites were never required
15 years ago, when I was using eMule, I made the switch to Torrent because Torrent was way faster for me. That's all.
ShareReactor was a user submitted index of content on the eDonkey network and its layout and functionality were clearly an influence on the not-yet-created Pirate Bay: https://en.wikipedia.org/wiki/ShareReactor
When SR was at its peak, that was also ed2k's peak. In my teen and possibly post-teen years, I managed to upload some hard to find (pirated) pieces of software on the network and indexed on SR.
A quick search some months back showed there were still some of them available (via a tag I used) which was a pretty fun discovery considering they're almost 20 years old.
15 years ago, when I was using eMule, I made the switch to Torrent because Torrent was way faster for me. That's all.