I wouldn't stop a friend from shooting any distance, but if I know it's a friend who never goes to the range, I wouldn't hunt with them again. I know a couple guys who will blast 800 yards or more...never heard them talk about going to the range (they also blast 800 yards because they won't get out of their trucks to hunt). Personal or not, I don't see how that could possibly be ethical when you have a minimal chance of hitting a quick kill shot.
I shoot fairly regularly and I'm comfortable up to 400 yards. It may be silly, but if the shot is 401 yards, I'll find a way to close a yard or two. I just have to set a limit in my head or else I'll get tempted to fire some rounds much further than I should.
Archery I'm not as good at, and my limit this year was 40 yards...I threw an arrow at an elk I wasn't able to range because he was big and I had 2 seconds to react...hit him in the shoulder and it bounced off...shot was 50 yards. I learned a valuable lesson, and it seems I just hurt the poor guy's shoulder. I felt terrible. Hopefully I won't let a big rack blind me to my ethics again.
I don't think it is ethical for 99% of hunters to shoot more than 300-400 yards. They don't train enough. But I would never say anything to one of them. I just choose to hunt with other people who hold my same ethics, and hunt the same style as me (i.e. put on some miles every day!).