I would't like if a startup fakes. They'd lose my credibility. However, some of the examples seem reasonable - like the case of reddit. It is more about providing value to the early adopters - clearly reddit needed more users to contribute, so no harm in creating fake users to seed the content. The example of PayPal seems bad - i am not sure if PayPal was a paid service for merchants back then, but if it was, they were just being evil.