A directory wouldn't be there to exclude anyone actually producing content of worth. It would serve as a gatekeeper to keep out plagiarism, spam, and utter tras

A directory wouldn't be there to exclude anyone actually producing content of worth. It would serve as a gatekeeper to keep out plagiarism, spam, and utter trash. And people could create networks of sites based on their own real-world webs of trust, which vouch for one another. Personally I'd rather see a standard which allowed you to add as many directories as you wanted to what your search engine would metasearch across. This also avoids the political problem of "who decides what's trash" -- if you want to add a directory whose main deal is they'll add literally any site, you could. If you want to only add directories which don't allow any <insert hated party> leaning content, you could do that.