I swept a whole host of issues under the rug, not all of which are related to key finding. Let's see forward secrecy (one of the bigger ones). The internet works this way: when you send a message, it gets delivered to the recipient, and a copy is sent to the NSA.

Without forward secrecy, getting Laura Poitras' key will enable the NSA to read all past communications. They only have to seize her computer when it's still on, and the key is still in memory somewhere, or compel the poor journalist to give up here keys (possibly using that "non invasive" waterboarding torture, and justifying it with suspicion of helping terrorists).

Now if Laura kept the decrypted messages in her laptop, forward secrecy wouldn't do anything, but if she properly deleted them, it would be a shame if the messages were nevertheless at the mercy of the attacker.

---

As for key finding, well… the simple solutions do work pretty well. Snowden for instance didn't find Poitras' keys lying around on the internet. He asked someone he trusted would give him the right key.

How are you sure it's her key ? That's the real problem

The one that gets published on multiple social media accounts, a personal website and in the New York Times?

It isn't real ambiguous.

For instance, Snowden had someone tweet a key fingerprint: https://theintercept.com/2014/10/28/smuggling-snowden-secret...

That's a pretty good way of making sure, because you defer trust to the intermediaries. While it definitely works for high profiles like this, it is obviously not scalable for larger audiences