This isn't hardware versus apps — it's about what you own. Smart TV, mobile and web apps put your service on screens subscribers already have. They matter for reach, and you should ship them. But on those platforms you're a tenant: the device, the home screen, the rules and the data belong to Samsung, LG, Google or Apple.
Your own STB is the exception. It's the one device that's entirely yours — your launcher on boot, your update schedule, your DRM, your data, your billing. It's where you guarantee the experience and anchor the subscriber relationship. The winning setup pairs a controlled, branded box at the core with apps everywhere else for reach.