We are also changing how remote playback works for streaming personal media (that is, playback when not on the same local network as the server). The reality is that we need more resources to continue putting forth the best personal media experience, and as a result, we will no longer offer remote playback as a free feature. This—alongside the new Plex Pass pricing—will help provide those resources. This change will apply to the future release of our new Plex experience for mobile and other platforms.
Indirect Playback goes through them first. Also, they host DynDNS for the Plex media server to make accessing it remotely from apps easier.
The second thing is a joke to host and requires no resources. The first one can be a significant resource usage item.