Because DRM is decreasing sales, not increasing them.
> lets say we have a "perfect" DRM method.
There is no perfect DRM. But let's say there is very hard to break DRM. That means very abusive, extremely privacy invasive policing method. It would fall even more into the crooked territory.
> If DRM didn't increase sales then I don't think you could make the argument that every single publisher who uses DRM is doing it for reasons other than sales.
Why not? I could make an argument that some do it out of ignorance, and the rest (of DRM users) are crooks. That's exactly what I'm saying. I.e. those who aren't dumb are using it for crooked reasons which have nothing to do with preventing piracy (I listed such common reasons above). And the rest (who use it indeed for sales sake) are digital Lysenkoists.
