I don't think that astroturfers claiming to be pirates who "gave in and bought the game because of the DRM" is what people have in mind when they say reliable data.

Sure I don't deny that those people actually exist but I do also know that there is an incentive to push that narrative because they are spending money or time (in the case of In-House DRM) on implementing these measures so they got to make it seem as worthwhile as possible (especially in the case of publicly traded companies with shareholders).