I've used this, as a 'buyer' (and have bought in several cases) for things like books and detailed articles written by independent people. One extra benefit is

I've used this, as a 'buyer' (and have bought in several cases) for things like books and detailed articles written by independent people. One extra benefit is 'please sign up for email updates' which while in almost all cases not mandatory, comes with text like "stay up to date" or "receive insights". I usually do sign-up, and this keeps the person providing these updates with another potential customer for other stuff, and me with usually useful (as I've self-selected as being interested) and interesting updates. Win-win.