You don't need the secret human sources any more.

You used to need them, because journalists had the distribution and the sources didn't. In a word of printed newspapers, you couldn't get your story distributed nationally (much less worldwide) without the help of a journalist, doubly so if you wanted to stay anonymous.

Nowadays, you just make a Substack and there's that.

See that recent expose on the Delve fraud as just one example. No journalists were harmed in the making of that article.