Volume. A long time ago, ten replies was huge, not a thousand.
Join the communities, follow the people, and start conversations where the world is still small, you'll find what you are looking for.
The filter is your friend, social sites are not the only sites (federated ones included), and there are many destinations to participate as long as you dont hunt for exposure to the masses.
Edit: Friendly reminder that IRC, web comics, and niche forums still exist.