8K decoding needs HW acceleration, unless having 8-16 cores with AVX-512.

Yes, but that's way out of budget for most consumers.

Actually not really, Lunar Lake chips with Xe2 graphics have VVC decoding in hardware which can do 8K.

https://en.wikipedia.org/wiki/Versatile_Video_Coding

They were likely saying that 8K displays are way out of budget for most consumers.