I remember those sites, leo, and perhaps 7-10 years ago, many of the freely shared passwords worked, even with the largest pay-porn sites. I know from experience!
However, all good things must come to an end, and programmers developed software/apps that became increasingly fast and accurate at identifying and shutting down passwords being overused / used at same time from different addresses, etc.
Shared passwords that once lasted weeks soon were disabled in days, and finally, mere hours. Only the least sophisticated (and least interesting) sites remained unprotected, and traffic to the sharing sites evaporated.
Yes, it was fun to feel like a safe-cracker, getting that rush when a site let you in. But today you have, above all, lovely torrent sites (ahem) that offer many of the old benefits, using different techniques and technologies.
I would say, "be nostalgic for the old, but thankful for the new"!