This is exactly what "shifting baselines" is about. Blue whales appear to have "rebounded" to a population size worldwide of about 12,000. But as this article says, over 350,000 were harvested previously. So we're still talking about a population that is well below 10% of its original abundance.
Yes, I know there are those who would say, "we need to celebrate every little success," but what happens when you naively celebrate the news of a tiny uptick, then find out the species is so sparse that a single disease can wipe it out? Shifting Baselines is about keeping things in perspective since that's the only hope for making sense of ocean decline and eventually drawing a halt to it.