I don't know about the rest, but for incentive to opt-in, I could see it as a way to keep up to date on new products. I'm starting to get into woodworking, and I've voluntarily signed up for advertisement emails from some retailers because I want to know when something I need goes on sale, or when a new product comes out that would be useful. If I could pick which advertisements I'm targeted with, I'd be happy to turn off my adblocker, but since the current option is either block all ads or have pervasive tracking for targeted ads chosen by an ML algorithm, I choose no ads.