They use this claim so that they can bastardize a species more than humans already have.. You think living in a cage saves a species? If they run a program that is out doors away from human interaction and does release and have a great turn over rate-- then they are serving a purpose.. If they are locking up the last surviving members of a species for human entertainment.. and feeding them into obesity and atrophe-- they are not being beneficial. There's a book I can't remember the name of right now on the exotic animal trade (specifically marsupials and reptiles ) it is how they bastardized the image of saving species in order to collect and capture creatures from the wild and place them in zoos-- many of the times paying locals to destroy whole colonies of these species in order to find several of the most aesthetically appeasing members. It is all a farce that many buy into. It's no different than seaworld supplementing the dolphin culling in Japan in order to get a few good specimens.