....read a question posed onetime , is keeping an animal alive in captivity but extinct in the wild really much of an accomplishment ?
Hell yes it is! How is this even a question? On one hand we have a species gone from the face of the earth forever, never to be seen anywhere ever again, and on the other hand we can have steady captive breeding assurance colonies all over the world, with endless possibilities for reintroduction if the local problems can be resolved and correct methods figured out. Might reintroduction fail? Yes. Of course it might. So what? Try again later or in a better spot. Learn from the failure and figure out how to do it better. Solve the problem(s) that made them go extinct in the first place. If there are none breeding in captivity, then there is no possible hope of saving the species.
Lots of reintroduction programs around the world have been successful. Sorry they haven't figured out how to do it right with your local Blandings turtles, but that is no reason to discourage any other attempts around the globe.