Also, who’s to say they “developed” that? That makes it sound like they’re dealing with something completely new (fits into man-made climate change narrative). Is it possible that through millions of years of evolution the earth had many such warming experiences and they developed this technique well before we arrived on the scene?
If you'd RTA you'd have answered your question. We've long had evidence for this type of recovery happening. The problem is that the evidence is from the Paleozoic fossil record. It's vanishingly unlikely that /no/ corals ever undertook this process in the past 300 million years but it's not typical behavior and it's extremely significant that it's been observed in modern corals.
We know that catastrophic climate change has occurred in the past. Climate scientists are not proposing this is new on a geological time scale. But it's new to us and to most extant species. We don't all have these tricks up our sleeves.