To me a website that grows too much is dead. Reddit has reached that phase now. Started out great but has turned in to Facebook
I'd agree and say I don't think reddit has the quality of discussion in posts or comments that it used to.
1. No politics
2. Nobody trying to sell you something or promote themselves
3. Based around a single, external topic, usually an established IP
Examples: r/Factorio, r/asoif,