Perhaps I'm painting with too broad a brush, and some subreddits are valuable?
> curated content from true experts _tends_ to be a lot better (finding those experts is obviously hard)
Yes! I would love a search engine that is limited to high-quality sources. Technically it seems simple: Just limit indexing to expert/professional/high-quality domains. If I look up something in the field of science, show me results from Nature, the NY Times science section, AAAS, conferences, Scientific American, etc.
Some valuable content would inevitably be omitted, but we live in an age of information overload - I would much rather omit a few things than deal with the 99% low quality info.