You don't understand the mindset of some hardcore collectors, especially of unreleased/rare games in Japan. From what I've read, it takes someone on the outside years to get inside those circles, and if they have one whiff of someone "betraying" their trust you are out, done-zo.
It's more a case of being part of a club, or niche group, that prevents wider sharing. In these cases, the things that do get out are precious indeed. Getting ultra angry at things is not worth it though; just enjoy what trickles out because these are long, slow affairs (one person confided in releasing roms at a process that takes years in order to remain undetected).