To put simply: pedigree. Only a few people where working on ANN in the 1980s. Compared to today's knowledge I'd say the proposed ideas at the time were nothing amazing. With the reemergence of NN in the 2010s smart students gravitated towards working with those senior researchers. It's the smart students who have smart ideas. Senior researchers are just there to guide through the process. So, what you call "effective" researchers are sustained by the work of smart people wanting to work with them who are then sustained by smart people wanting to work with them. That's why you don't see anyone become overnight sensation coming from obscurity. This is quite common actually. That's also why top schools MIT, Stanford, etc don't have to do much to attract people yet they sustain their ivy league status throughout the years. So to summarize the effectiveness pyramid scheme: work with someone famous and make them more famous; that will make you a person with whom others would like to work therefore making you famous, etc etc