That ethical duty thing is always a slippery slope. Since we all essentially have our own idea of what's ethical.
If I want to take a .25-20 Winchester for deer, there are some people who would scoff at that. Saying that there are much better options etc. Even some who would bring ethics into it saying that using a rifle like that is an ethical problem because I have other options better suited to the task and which have a much lower chance of wounding game. And they're right. All things being equal (shot distance, angle, deers body language, etc) a .300 mag at 35 yards is going to have a lesser chance of only wounding an animal than a .25-20wcf.
But I don't think that means it's unethical for me to try to take a deer with a .25-20.
Match your shot limitations to what you're using. And don't have unrealistic expectations or take unrealistic shots.
An elk hunter could hunt their entire life with a .30-06 and do just fine. Or with whatever variety of .300, or a .338, or a .35 or a .375 or a .270 the list goes on...
As long as they match their expectations and shot choices with their chosen rifle they will be fine.
Now for the guy who wants one rifle to hunt with and wants the best, or as reasonably close to the best, option available for him then you start looking at everything with a fine tooth comb and picking apart all the different load options and combinations available and trying to decide what suits your needs and what is best matched to the game animal(s) that you'll be hunting, the locations and the distances and angles you expect to encounter.
-Jake