>If a field accepts P=0.05 as significant it means 1 in 20 results can be false positives just by random chance.
That is not the correct interpretation of a p-value. See the ASA's statement on p-values.[0]
>Researchers often wish to turn a p-value into a state- ment about the truth of a null hypothesis, or about the probability that random chance produced the observed data. The p-value is neither. It is a statement about data in relation to a specified hypothetical explanation, and is not a statement about the explanation itself.
Moreover, while it's fine to suspect that p-hacking took place with p-values just under 5 percent, it is merely a suspicion and nothing more. Throwing out p-values you don't like without further evidence is a different sort of violation of the methodology; it is like p-hacking in the other direction.
>The right threshold should really be an order of magnitude lower.
This is false. Again, see the ASA's statement.[0]
>Practices that reduce data analysis or scientific infer- ence to mechanical “bright-line” rules (such as “p < 0.05”) for justifying scientific claims or conclusions can lead to erroneous beliefs and poor decision making. A conclusion does not immediately become “true” on one side of the divide and “false” on the other. Researchers should bring many contextual factors into play to derive scientific inferences, including the design of a study, the quality of the measurements, the external evidence for the phenomenon under study, and the validity of assumptions that underlie the data analysis. Pragmatic considerations often require binary, “yes-no” decisions, but this does not mean that p-values alone can ensure that a decision is correct or incorrect. The widespread use of “statistical significance” (generally interpreted as “p & 0.05”) as a license for making a claim of a scientific finding (or implied truth) leads to considerable distor- tion of the scientific process.
In short, these things often require a strong statistical literacy to interpret, which most people complaining about p-hacking do not possess.
[0]https://amstat.tandfonline.com/doi/pdf/10.1080/00031305.2016...