The placement of financial incentive at the user should help them invest in combatting spam and returning good results. The results are already pretty solid.
Money easily creates perverse incentives in media. The advertising driven model is the easiest to scale. You lose the friction of signups and people don't want to pay anyway. They'll happily blow $50/month at Starbucks but $10/month for media is too much. Unfortunately the advertising model places the incentive around capturing user attention rather than delivering anything useful, so it incentivizes the media equivalent of empty carbs and sugar.