I might be an atypical user (?), but none of those sites appear to do the two things I and everyone else I know use Craigslist for: 1) buy/sell used goods; and 2) find long-term apartment rentals.
For #1, eBay seems to be the only real competitor, and does non-shippable goods poorly (Ebay Classifieds has never really taken off). For #2, I don't really know of any (AirBnB and Couchsurfing are good for trips, but not really for finding somewhere to live).
I agree with you that none of these sites actually tackle the main uses of craigslist. I was merely questioning your assertion that you'd never heard of any of them :).
For #1, eBay seems to be the only real competitor, and does non-shippable goods poorly (Ebay Classifieds has never really taken off). For #2, I don't really know of any (AirBnB and Couchsurfing are good for trips, but not really for finding somewhere to live).