But why would they? Why not publish? The whole point of doing scientific research is to get your ideas out there. To use the reporter analogy used earlier, it would be like a New York Times editor writing an OP-ED piece and deciding to simply post it in his bedroom or on the bulletin board at a local library or something. It makes no sense. There's nothing wrong
with it and surely he would receive credit for it, but it flies in the face of the whole idea behind journalism. It makes no sense to hide your work as a journalist just as it makes no sense to hide your work as a scientist (national security, personal safety, and a couple other reasons aside).
Also, scientific discovers are not just someone figuring out something, writing down an equation, and boom, Nobel Prize. It's usually years of research done by more than one person (in high energy physics, sometimes even hundreds of people!). When a group of 3 people get a Nobel Prize, it is because the Nobel committee believes that they were the 3 biggest contributors to a significant field of study; none of them came up with 1 thing at 1 instant in time that made them worthy of a Prize.
Well if that's true then, what are they waiting for?