and it can't compete with eBay because ... ??
OpenBazaar is Bitcoin related , so basically if Bitcoin becomes mainstream then it would be totally competitor to eBay otherwise it won't so it's all based on Bitcoin it self and nothing else since it's the first shopping web of it's kind , but who knows ..; If eBay or Amazon suddenly start accepting bitcoin before OpenBazaar becomes popular then it may be useless for OpenBazaar then ;