Why Stack Overflow's Documentation effort failed -- a few thoughts from a technical writer's perspective

Stack Overflow, mostly known as a forum for answering niche software questions, recently tried to launch a Documentation component to their site. The goal of Documentation was to 'do for Documentation what we did for Q&A'. In other words, provide substantial, valuable information that could be the go-to source for tech docs instead of just one-off answers around niche topics. However, the effort failed and now Stack Overflow is sunsetting their Documentation.