This was over 10 years ago, but iirc the primary demographic was what you might expect: 20s to mid-30s living in urban areas, skewing lower on that spectrum.
Our data was almost identical to the article, showing the same imbalances.
I don't mean the generic demographic categories but rather similarity in behavioural patterns. Were these people terminally online, more or less attractive on average, had rich social life?
The article is really good on the product decisions but light on what kind of life and situation these users have.