Because if I introduced 75th level characters into a game then I would also be introducing 75th level (or thereabouts) dragons, which - as I pointed out - would have natural armour bonuses that exceed the most powerful armour that can be forged by mages and godlings in the setting.Why are you so fixated on what is power level x as compared to power level y? I don't understand.
Which is to say, the issue that I dislike - the simulationist veneer of "natural armour" - would still be there.
If you're still confused by my concern, I recommend [MENTION=6801286]Imaculata[/MENTION]'s posts above. Imaculata doesn't get irritated in the way I do because he (? I apologise if that's an erroneous gender attribution) is able to treat the natural armour bonuses as purely mechanical devices to ensure the game maths works properly. I can't muster the same sanguinity, but Imaculata's response shows a clear understanding of the issue I'm raising and addresses it completely sensibly (and without any frustration on my part at least).