Time was Nikon was the only camera choice of professionals and Canon ran a distant second. I don't know if it was the bayonet lens lock instead of breech ring; glass; features or pros liked the distinctive view finder on the Nikon F. I almost said "original", but the really old viewfinders for the Nikon F used an exterior rather than reflex mirror..
Some of it went downhill when Nikon introduced "E" series lenses built to a cheaper standard (nylon/plastic focusing helix rather than brass/aluminum, etc.) and it left the realm of "Pro gear" and broadened into the consumer sector.
Canon seems to be whomping Nikon with that is thought to be a nicer mirrorless camera, the "L" series pro grade lenses (identified by the red ring). Even so, Sony seems to be at the lead in mirrorless, at the cost of a less extensive system. Now, rather than being seen with the Nikon F, cool is a nice long white telephoto, preferably with an absurd aperture like the 300mm f2.8.
Moderately priced scopes were just another example of Nikon leaving the realm of "highest end only stuff" into broad based consumer goods.