I think you are underestimating the number of people who own either a Switch, PS4 vanilla or something like a SNES Mini and still want to own a decent to high end 4k TV for different uses. I mainly game on a PS4 Pro (no issues there) and Switch, but also play on SNES Mini and occasionally Wii U. High input lag is a death sentence for me. A high end set should be versatile for any kind of use. That's why Sony's upscaling of lower resolution content is second to none. Input lag should be the same, but isn't.
Haha, no I'm not, I'm one of those people, but if you're only really into high end console/PC experiences, AF8 is a good option.