That's a false equivalence. The blue whale is spectacular in that it's literally the largest animal to have ever existed. By virtue of that, it's bound to be in textbooks and record books and whatnot. By contract, bottlenose dolphins are less conspicuous, and they were 100% brought to the general public's eye by shows like Flipper the Dolphin, which in turn wouldn't have existed without the Miami Seaquarium.Has anyone heard about the blue whale?
Orcas were similarly brought to general public awareness by dolphinariums. In fact, before the practice of keeping orcas in captivity, orcas were considered a pest species; the US Navy literally used to use them as target practice, and plenty of countries like Norway and Canada considered culling them to reduce their impact on fishing operations. They were considered to be worse than value-less before the dolphinarium industry turned their efforts towards them.