Denon has made high-end integrated amps (like the $8K MSRP Yamaha S-3000 Integrated). And Denon has made some expensive amps and pre-pros in the past.
But for the most part, like Sony, Denon only makes AVRs. So again, how can a company be considered high-end if they only make AVRs?
Marantz is considered high-end because they have expensive Pre-pro, Amps, Integrated Amps every year.
But because Marantz is associated with Denon and also sells some affordable AVRs, Marantz is not quite high-end like Anthem.
So "high-end" is about making fewer products that cost a lot and unassociated with other brands that are not considered high-end.