From BItshares:
We believe that the BitShares network can offer each referrer an average value of $80 per member they sign up, or $40 if they go through an affiliate. This value is realized over time based upon the actual usage of the customers. Even if a customer thinks we are overestimating by a factor of 4, BitShares still offers a larger incentive than PayPal did.
So the minimum lifetime value for Bitshares was $80 based on actual use. On the other hand Steemit is a lot easier to monetize and the use is very different so it's hard to determine what the value is. I would say it's probably more than $80 because of the lifetime value of the content they could generate but because the content could be basically anything, I can't really determine with any accuracy a lifetime value of a content producer, it could be in the millions for some and then for others not as much, and this would effect the average value.
So for Steemit to have a value per user of $25,878 does make sense when you consider the early adopters probably aren't ordinary people. Most of us have advanced degrees, very specialized skills and knowledge, and this would be reflected in our posts. Even people who post on travel topics or who post on political topics, aren't just the typical blogger. We have people here who have very unique experiences, knowledge, skills, perspectives, but over time this novelty might wear off. When the Internet first came online or even when Facebook first came online, the average user was in academia, in the ivy leagues, it didn't begin to represent the average person until a lot of people were on the platform.
So it could be that for right now the average blogger on Steemit does not represent the average blogger on the Internet. More data and statistics have to be analyzed because I'm not sure of how to interpret this yet.
Reference
https://bitshares.org/referral-program/
https://en.wikipedia.org/wiki/Customer_lifetime_value
https://en.wikipedia.org/wiki/Gompertz_distribution