I routinely read the news, and I've been taught in school that critical reading involves doubting and focusing on facts, sources and proofs. No sources and verifiable proofs? No facts.
Which is why the journalist put emphasis on his sources behind the missile attack: he knows how much sources and proofs are important.
If you can fake screenshots, why not fake them, which is something that can be at least analyzed for tampering?
Even more: the author mentions X public replies, where are the links?
Whether or not it should work that way is a separate question. But claiming that raw sources not being included is cause for suspicion is incorrect.
In such cases, the journalist likely will publish raw data/screenshots, since they're functioning both as the source and the reporter.