“Why Do So Many Music Venues Use Ticketmaster?” “What’s It Like to Train to Be a Sushi Chef?” “How Do Martial Artists Break Concrete Blocks?” If you were looking for answers to such questions 10 years ago, your best resource for finding a thorough, expert-informed response likely would have been one of the most interesting and longest-lasting corners of the internet: Quora.
A Fediverse version of Stack Exchange would be easier - since the content is creative commons you could start with a full catalog of already answered questions…
But honestly, competing with the real Stack Exchange on one end and Large Language Models on the other end… never going to work.