HBO has a mobile app. It lets you watch shows, and it supports Chromecast. Really, that's all that matters here. There's little else it needs in the way of features that will determine whether or not users will turn to it when the opportunity comes to spend some time with HBO. The real question is - do you really want to watch all those sex scenes on the family TV?
Let's go through the checklist. Is your mom home?
What about your dad?
Heck, let's change roles for a second. Would you really want to walk in on your daughter watching this?
Yeah, now would be a good time to go give the app a try. For everyone's sake.