From the article: "An estimated 30 million small-scale fishermen and women depend on reefs for their livelihoods, more than one million in the Philippines alone. In Indonesia, fish supported by the reefs provide the primary source of protein."
"Well don't worry, we'll just get food from somewhere else" is not a real answer. At some point, life on a dead planet just isn't worth it anymore.
We are looking at the devastation of an entire habitat. Many species that rely on that habitat may cease to exist. As a consequence, many species that eat animals from that habitat may disappear too.
Worst-case, we're faced with the disappearance of an entire food chain. And since many large ocean species travel the entire world, the consequences will not remain local.