It makes a lot of sense for non-gaming tasks. Text looks great and non-fractional scaling makes a big difference. Try it for yourself, there are several non-"gaming" (60 Hz) 27" 5KUHD monitors out there. And remember just because you can't notice a difference doesn't mean no one can.
And for gaming: most GPUs can't drive most games at native 4KUHD. Some form of temporal upscaling (DLSS, XeSS, FSR, TAA etc.) is usually required anyway, and whether you're upscaling to 4KUHD or 5KUHD from the same internal resolution doesn't have a big performance impact.