The digital transformation has fundamentally changed relationships of observation and influence in the public sphere. In traditional mass media, professional journalism mediates between sources and audiences and makes publication decisions alone. On the internet, this gatekeeper paradigm has been partly replaced by a platform-based network paradigm, in which constellations are more diverse, dynamic, and often unmediated. The role of mediating third parties in actor constellations as well as in intrasystemic and intersystemic relations is discussed. In this context, the work of Georg Simmel is taken up in two ways: Social forms or modes of interaction help to systematize the dynamics between actors. In addition, Simmel’s approach to the mediating third party is revisited. In the network paradigm, mediation includes moderation and navigation in addition to news provision. Numerous symptoms of the crisis in the digital public sphere raise the question of the need for reform of journalism and platforms.