Even if they get past the security issues and limit it to non-rooted Widevine L1 certified devices, it's easier said than done. A lot of 3rd party devices do not natively decode AC-3 audio and rely on HDMI passthru, and not all TVs can decode AC-3 over HDMI (especially older Samsungs), many don't ship with a hardware MPEG-2 decoder for SD or OTA channels via an AM21/LCC connected to earlier model Genies, many ship with MPEG-2 and AVC decoders that can't do hardware deinterlacing of 480i and 1080i channels, and for the 4K channels an AC-4 audio decoder is needed which is even rarer.
Streaming platforms have the ability to offer alternate streams with deinterlaced H264 video and AAC audio to get around device codec limitations, but like what the HDHomeRun has to deal with, they don't have that option when you are passing feeds as is from a broadcast, cable or satellite source, and then you have to deal with certain devices like Roku that forbid developers from including binary libraries to support codecs that their internal player can't, along with lower end devices that don't have a CPU powerful enough to do software decoding or deinterlacing at 60 fps.
They used to support using your TV as a client if it supported RVU, but that relied on them waiting for 3rd party device manufacturers to approve and release updates, and many of them refused to support feature updates for models that are more than a few years old.
