I'm surprised that Stack Overflow/Stack Exchange wasn't in the list of platforms; their policies against eg. duplicate questions are frustrating to users expect

I'm surprised that Stack Overflow/Stack Exchange wasn't in the list of platforms; their policies against eg. duplicate questions are frustrating to users expecting a forum but are explicitly designed to generate content that's useful in the long term. I have no idea how many man-hours (man-centuries?) of effort have been spent by programmers generating post-hoc documentation within the SO platform. It's unquestionably useful today, it's somewhat distributed by mirrors and the database export, it has an API, but there's no question that if SO folded tomorrow that a lot of utility and a lot of effort would be lost. However, I am confident that if SO did not exist and those contributors did not become addicted to the dopamine boost from "+10 Karma!" notifications that they would not have instead created permanent, Google-able, individual blogs with an equivalent amount of utility as what SO provides.