Umm, isn't that exactly what Facebook apps like FarmVille were? I don't think Facebook charges app developers to publish apps on their platform, and the app was monetized.
Farmville is ancillary to Facebook as a whole. Those users might play Farmville but also read up on their feed or click through their friends' posts, thereby allowing Facebook the chance to show ads.
Apollo et al are different in that they are packaging up the entire experience wholesale, they are not ancillary. There is no way for Reddit the company to show ads through third party clients (the client could simply block ad posts if they wanted to).
Apollo et al are different in that they are packaging up the entire experience wholesale, they are not ancillary. There is no way for Reddit the company to show ads through third party clients (the client could simply block ad posts if they wanted to).