Good point. However, eBay was a classified and auctions site and paypal was complimenting it. The examples suggested by OP are more competitive in nature. The o

Good point. However, eBay was a classified and auctions site and paypal was complimenting it. The examples suggested by OP are more competitive in nature. The only case I can think of is Instagram on Facebook. However, even in that case, Instagram was providing an equivalent, if not superior, user experience within Facebook. I believe it turned out to be a smart choice in the end.