For whatever topic I'm interested in, I'll search reddit to find where the hardcore fanbase is. For example, if I'm interested in flashlights, that would be candlepower forums.
The echo chambers have grown to substantial epicenters now. Give me a search engine that finds those and puts search in it and I'd pay $5 a month for that because at that point, you've found the expert and active community and looking at cutting edge knowledge bases. I suppose it's what the academic and scientific communities used to be before subsidies and blue church ruined it.