Suggesting that beliefs on captive suitability for all species must be static across the board, to avoid hypocrisy is so simplistic as to appear hypocritical in itself - or at the least disingenuous - as if we don't ALL make housing and care decisions based on species differences. Learning and suggesting care according to each species is why most people are on the site in the first place.
Cetaceans need a lot of both free and structured (by them, not us) interaction and exploration with a group of their own kind in a complex natural environment, to mature properly. We can't provide anything near that in captivity, anymore than our own child could be provided what they need from an alien species that knows little about us.
Humans that don't get regular interaction and upbringing from their own kind demonstrate stunted mental growth, reasoning, and reduced ability to learn language, social, and problem solving skills later on, so why must it be different for another similarly intelligent, social, and physically active mammal?
Thriving in comparison to? It has been demonstrated through scientific research and observation that cetaceans in captivity often have physical, mental and social shortcomings that aren't the norm in their wild counterparts. Whether you believe that's even an ethical issue or not, those things have been observed. And that's only through what can be understood, since we really don't know enough to get the whole picture.
Breeding isn't a complete indication of happiness or health. Many organisms find a way to procreate despite the odds, and it's a strong natural drive to live and procreate. People in desolate starving African countries still manage to do it without the help of scientists and special caregivers.