[wutbrodo]

I'm not sure that distinction is as clear as you're describing it. Pretty much anything that creates positive feedback has the potential to create addictive behaviors, and (most) porn certainly isn't going for a realistic depiction of a healthy sex life. The design of porn sites, like most content websites, are oriented around continued usage. Trying to get people to use your product more doesn't seem technically distinguishable to me from "engineering to create addiction", and it's not clear to me what you think makes the two examples you describe distinct from each other.