Nothing in the spec stopping an OEM from putting a DP connector on their HDMI sink (TV). It doesn't even have to be HDCP 2.2, but you'd likely want it. And we fall back into the same anti-user trap of DRM. Also the spec won't let you easily add non-HDCP ports to a repeater though, without reducing functionality. And it gets weird if you mix HDMI and DP on the same HDCP compible repeater so I don't think I've seen one on the market. (Repeater spec limitations means A/V switch will have some difficulty)
Not worth the $1-$5 to add DP input, when the margins on TVs are already pretty thin. So finding them on digital signage is more common, but the implementation of DP (and HDMI) tends to be less cutting edge on digital signage. Until recently getting HDCP 2.2 to work was a rare feature, locking you out of some 4K content, and variable refresh rate is currently very rare on digital signage.
I think consumer markets like to make what they made before. And during an economic downturn they aren't going to invest much effort into marketing new features of dubious value that they will have to explain to end-users. But in a perfect world, our TVs and PCs would all use the same connectors and superior signaling of DP. The DP alt mode of USB-C could drive us there, especially now that HDMI alt mode proposal was killed off. (shortly after I spent a fair bit of effort implementing it for a customer demo)