The point of the website is to collect information about drugs for education and research purposes. It's a 501c3 nonprofit, which operates explicitly for public education. It's funded by donors, not by consumers of the info collected.
tl;dr - I seriously doubt any of the users wants to be identified, much less compensated for providing "data".
On point though, many of the chemicals in question aren't legal so not sure how much users would want to be identified..
I'm a very experienced psychonaut and even I won't dare touch that stuff. One of my friends did and just watching him on it made me never, EVER want to do it.
e: From the original paper:
> Rigorous quality control is conducted by trained experts with careful consideration given to “quality, credibility, and focus on effects or outcomes” (www.erowid.org). By means of that mechanism, all reports that provided the basis for the present investigation have successfully exceeded a standard quality filter.
Totally.
maybe the AI researchers are from the same school of thought. having bad/unvetted medical data/advice on psychedelics would be better than no data at all, right? /s