The Tsu platform I used before Steem has some celebrities at the start, who I assume were paid, but they did not stick around. The rewards there (based on ads) were probably not enough and the audience may have been lacking too.
The delegation system we have is a great way to kickstart an account without actually giving them money. They can give out votes to fans.
I know of a few accounts here who have hundreds of thousands of fans elsewhere, but hardly engage on Hive. They may just have someone copying over posts for the sake of it. Audience really matters, but it is a chicken/egg situation. We need 'names' to bring in fans, but kickstarting that is hard.
A lack of a company to back things like marketing can be part of the problem, but it didn't help Steem much.
RE: Why is Hive not growing?