Craigslist is a poor website but since everyone uses them, everyone is locked into using them. Any site that helps people use Craigslist with other sites might

Craigslist is a poor website but since everyone uses them, everyone is locked into using them. Any site that helps people use Craigslist with other sites might cause people to eventually switch from Craigslist entirely. This applies to both finding listings and posting listings. That's why Craigslist is so litigious, even on the posting ad side. It seems hard to justify legally, but they probably figure small startups won't be able to fight them in court.