I went to a Ford vs Chevy event a few years back, the winner drove a mustang....with a chevy engine. Not the best comparison but I think I see your point.
When shooting a bottleneck cartridge out of a platform such as a contender or encore, the shooter still must contend with handgun style shooting positions. Sure the round may have more range but the shooter also has to deal with handgun style optics, which are still a challenge at longer distances. So there are things that keep it from being just like hunting with a rifle.
For the record, I have no issues calling it handgun hunting as long as the firearm has a handgun grip. lol just my .02