I have given a few O'Reilly DRM-free books to colleagues. Younger colleagues, who usually have never heard of an "animal book." I always point out where it came from, and suggest that if they like it, they either buy it, or buy something else from O'Reilly.

Maybe some did, I don't know. I suspect that the ones that didn't, probably wouldn't buy a similar book from anyone, not because of piracy, but because they just aren't into that particular kind of product. So no (real) harm, no foul.