Everything in science is about enough evidence beyond reasonable doubt, never a conclusive proof, especially so in social sciences. So everything is essentially "may" or "may not". To claim otherwise, is journalists' job.
"Once one says "may", all the evidence have been redacted. All the educated guesses, all the logical inferences, thrown out the window. With the empirical data, and the established theories, what can one conclude? Of course it is not impossible that the conclusions of one's analysis is incorrect, but that's an interpretation of the conclusions, which is up to the reader. Don't put words in the mouth of the reader. Especially not words of doubt, not after so many pages trying to convince the reader of the legitimacy of the conclusion of the analysis. With the empirical data, and the established theories, what can one conclude? Nothing? Ok, then put the "may" in there, so the reader knows the text was a waste of time to read..."
That's essentially the logic of what happens to scientific information as it passes through the media on to the layman: it ends up trivialised and truncated so that it can be presented as "scientific facts from recent research" in the latest Marie-Claire. Even Foucault bitched about that in one of his interviews. But then again, it helps "sell science" to the masses, so there you go.
That one can conclude nothing is a bit too dramatic. We can gather enough evidence to suggest that certain things are most likely to be true. Considering how much effort and rigour go to get to that point, and that at some point of time, it is bound to give way for better, or perhaps, entirely different results, it's decent enough. In reality, science is a lot of educated guesswork, just the way it is put together, the scientific method, makes it much more reliable than, say, gossip, but it is not inherently THE best or multi-purpose method of cognition. Trying to create a belief in the infallibility of "scientific proof" is what makes science scientism, a religion like any other. Do we really want that now?