Ben Evan's writing about the eternal conflict between getting the balance right between 'here's everything' and "here's a few we think works". Answer ? It's tough.
Looking at these companies, it strikes me that actually, saying that ‘Yahoo’s directory didn’t scale’ misses the point. What we’re really seeing is a trade-off between two problems. You can have a list, solving discovery and recommendation, but once the domain gets big then your list is either unusably long or partial and incomplete (and perhaps uneconomic to maintain). Or you can have a searchable index of everything but you’re on your own working what’s good and finding things you didn’t know to search for. Time Out is an interesting attempt to sit in the middle of that scale – enough coverage to be quasi-universal, and to promise something good nearby wherever you are, but also enough curation that you don’t just get 5,000 listings all with five stars. ProductHunt is an attempt to use community to surface quality at scale, as is Pinterest (both are a16z investments). In contrast, Canopy uses hand-curated selections on Amazon. The question for all of these: do you filter crowdsourcing down enough to get quality, or scale up editorial to get coverage, or you give up on coverage and do a purely curated product?
And … on a related note, Apple and Twitter versus Google and Facebook. It’s a similar conundrum discussed in Fortune.