The incentives of the researcher. You don’t want to be the guy whose lab produces ten failures and one success, even if that’s the reality of every lab.
The guy who doesn’t share the null results will look better than the one who does every time. Deans and chairs only know how to count one thing in tenure decisions - lines on your CV.
To put this another way, nothing stops this kind of sharing right now, and yet we have a well known file drawer problem.
If the proposed solution involves “oh let’s just completely change the social norms, despite the incentives of the individuals involved,” then it’s a non starter. The kind of sharing being proposed is that kind of idea.
>>Point 1 is really the one I don't understand. Is it medical/health privacy that prevents this? Surely no one expects unanonymized data to be provided. This is about teasing out bad research, not indicting anyone for the falsified sort.
What you consider “anonymized” is generally not what regulatory agencies will consider anonymized and the best sources for health data at scale are always governments. (Frequently they are the only sources.) The agencies are too risk averse about the potential harms from data releases, but that’s the reality. You can’t share it. You can’t even have it on your own laptop, encrypted or not.
Interesting data that lets you answer complicated questions cannot be made public. The more interesting and the more complicated, the harder the underlying data is to access and if you say you want to share it publicly they’ll laugh you out of the room. You’ll never make it through the already excessively burdensome IRB process.