Quora and Stackoverflow.
They used to be great resources/discovery websites. They still are but they bombard you with trying to sell you shit, and you need to KYC into even using/reading the platform. Knowledge should be free.
Discussion
It’s not fully developed, but I made https://askopenly.world
It’s a nostr based question answer service that’s completely private
Try it out and let me know if you have any feedback