"I see this attitude a lot online, and it's total BS. Just because you kill a lot of deer doesn't invalidate others experience. I'm a one deer a year hunters for the most part. It doesn't mean the opportunity isn't there to kill multiple deer on a yearly basis."
Experience has it's advantages. I see 5-7 deer shot every year with cartridges from .22 to .30 caliber(those are the calibers we're currently using). I see which bullets do what when they hit at this or that angle. I see how much internal damage occurs at various ranges. There's no replacement for this accumulation of knowledge.
" You might get to kill multiple deer, but I get the opportunity to kill multiple species of medium and big game a year and this year I'll be hunting bear, pronghorn, mule deer, white tail, and elk. "
I'm not bragging about my hunting experiences but I've shot a few of each of the species you mentioned. \
I've commented that my deer hunting is "grocery shopping" and most of it is exactly that--putting food in the freezer. I tend to use what is effective and efficient rather than something that sort of works if you're lucky. I can and have killed deer with almost any cartridge(only admit to what's legal BTW) but I've found that some work better than others. Sure, I COULD kill deer for the next 20 years with a .243 BUT I'd prefer a 25/06 because I know it will do the job more effectively (with cheaper bullets) AND I'm more confident in that capability.