As we are a performance provider, our service requires a large enough sample size to determine a consistent eCPM for your application on a daily basis.
We have found that advertisers are interested in buying in different forms (by view, by completed view, by clicks, and by installs). They will also pay differently for each form and for each geo. Instead of paying you a flat fee per view, we want to make sure you get the full share of your user and what he/she decides to do.
Therefore, we work off of a revenue share model. While some views may not result in any revenue, we have seen that for every 1000 impressions, we see market rate eCPM. The users who actually do meaningful actions make up more than enough for the users who don't, but we need a large enough sample size for you to see this happen.