In the case of Steemit we could be talking about content. Content attracts people to the site and makes the site sticky. Stickiness is based on a psychological effect which I could go into in future posts but it's based around reinforcement. Email, or Facebook timelines, are good examples because the intermittent reinforcement causes us to keep checking our timelines to see if someone posted something, or to see if we got likes (psychic credits).

Steemit has so much more power to become the most stick social media site on the Internet. Not only does it have the psychic credits in the form of likes, but it also has the attractor patterns both in the form of attractive tokens (Steem Dollars/Steem Power) but also in the content itself. People interact with Steem just to consume the content and as more people join and provide fresh content then Steemit becomes more attractive, more sticky, etc.

References

The Psychology Easel. (2012, April 22). Retrieved Summer, 2016, from https://taradeliberto.blogspot.com/2012/04/keep-them-coming-back-for-more_22.html