O'Reilly and NoStarch don't do it because they honour their customers. Watermarks are a disgrace and a potential risk for the customer, because they put the liability to protect the book from third party access onto the customer. I'm not going to accept this. I only buy untouched books. Calling books DRM free when personal identification information is stored into a digital file to restrict the customers usage rights is ridiculous. Shame on those sneaky publishers.