"Curation is a crawling problem, not a filtering problem" reframes the whole category. Filtering inherits whatever the parent index already decided existed, so you spend forever arguing with someone else's map of the web.

The part I would find hardest is that a small index fails differently for kids than for adults. An adult reads an empty result as the index not having it. A child reads it as the thing being broken, and there is no obvious way to say "we have not crawled that yet" that lands at eight years old.