I had not, and I see that you addressed my poser there.

From the abstract of a paper that you linked to:

a research finding is less likely to be true [...] when there is greater financial and other interest and prejudice; and when more teams are involved in a scientific field in chase of statistical significance.

This corroborates my suspicion that effect B is more important than A or C; competition for funding and prestige leads researchers to knowingly publish false positives.

Another somewhat relevant article and discussion thread is here, concerning declining standards in published research due to oversupply. I'm not sure if the writer has a good handle on the root causes of the problem though.