The Power of Many
At its core, a mediation platform allows you to easily integrate and manage multiple ad networks for your mobile app. Working with more than one ad network may sound painful but it is essential as your number of users and available ad impressions scales.
An ad network that yields a decent eCPM with 1,000 impressions per day may not yield the same results at 1MM impressions per day. Integrating multiple ad networks and testing new ones allows you to find the best source of buyers for your inventory; all publishers are different, just as the users of their apps are different.