I have this feeling too. Strongly.
Sure, existing Blu-Ray 1080p is not H.265 but UHD already is, of course. So streaming 1080p with H.265 is plenty viable.
Streaming 4k is … a joke, really. Way too bandwidth intensive unless you choke the bitrate down so far that the quality would be crap. But hi-res crap!
I agree with @stusser that the vanilla iPhone 8 is really a 7s. I suspect supply constraints, plus difficulty of doing touchid on an “all screen” phone, forced them into this X scenario.