Great idea. Reminds me of a previous HN comment [1]:
How to build the next Google: all good results these days are within
communities, and Google search has become useless for most of these
searches.
So don't build a search engine: build a "rotten tomatoes
for X" where the sources for each X are "the top N
subreddits/communities/editorial-sites/forums for X".
I’d be curious to know how you plan on covering costs.
[1]: https://news.ycombinator.com/item?id=24714546