That's a good question. A slightly different question that might help you to understand what is happening in Australia with this legislation is "What was news?"
Facebook and Google between them receive more than 80% of all digital advertising dollars spent in Australia. [1]
This advertising revenue used to be known as "rivers of gold" when it flowed 80% to newspapers and television, in the decades before the internet existed. In those days, the advertising business was coupled to journalism, because journalism is how media businesses got their product into peoples homes and living rooms every day.
20 odd years ago, the Australian newspaper business began to be hollowed out by new competitors on the internet, such as Seek.com.au for job ads, Domain.com.au for property ads, carsales.com.au for automobile ads, eBay.com.au for the rest of the classified ads, and google and yahoo for display ads. The dozens of pages that used to make up classified ads in newspapers disappeared. As the rivers of gold dried up, the number of journalists employed in Australia declined dramatically.
Whilst you are correct that Facebook and Google don't actually publish news, they do receive the rivers of gold in advertising revenue that once funded journalists wages. This new legislation pretends to redress the imbalance that lead to the decline in journalism by diverting advertising revenue back to the old man who owns most of the newspapers in Australia. [2]
The old man's business doesn't employ half the number of journalists as it did twenty years ago, and the new legislation doesn't require him to hire any more.
[1] https://www.adnews.com.au/news/chart-google-and-facebook-s-s...
[2] https://www.theguardian.com/media/2018/sep/20/very-australia...