How many you gone to steemit just to check your account balance?
Probably more than you would like to admit...
The truth is that we will rarely do anything without an incentive to do so, it is one of the most basic principles of economics. Many other social media platforms have failed because user had no incentive to use them. If you cannot draw new members to your platform, it will die off.
Steemit approaches this problem by attracting new users through the offering monetary rewards. When most of us heard about steemit, it was probably something along the lines of "you get paid for writing stuff." What makes steemit so powerful is that it supports good content by allowing users to upvote, which generates income for the author.
This approach works better than any complicated youtube algorithm, because it directly awards the author for good content, not for getting a lot of views or having clickbait. I predict that because of all the positive reinforcement for good material directly from the steemit architecture, steemit will become one of the most successful communities in the near future.