Because you used, word for word, a common line used by climate change deniers. And climate change is what's destroying the reefs (both the increase in temperature and the increase in carbon dioxide (the main cause of the increase)).
They describe it in rather balanced terms:
The reef's northern and central parts have the highest amount of coral cover since monitoring began 36 years ago.
But coral cover in the southern part of the reef has decreased.
The new coral is particularly vulnerable - meaning the progress could be quickly undone by climate change and other threats, officials say.
The story adds
The reef has also been damaged by coral-eating crown-of-thorns starfish and tropical cyclones which generate damaging waves.
Much of the new coral growth - a species called Acropora - is especially exposed to the reef's threats, said Dr Mike Emslie from Aims.
"This means that... future disturbance can reverse the observed recovery in a short amount of time," he said.
Which doesn't seem to justify your suggestion
No, they really don't think the Great Barrier Reef is likely to rebound in the future. I wish we could all feel more optimistic but in this case I just don't think that's justified.