Basically what we have here are two different preconceptions.
Some people think that DOS is a game where any approach is valid, as long as it gets the job done.
Some people think that DOS is a hack n slash game where you can occasionally use stealth or diplomancy. (most crpgs in history have been this kind)
For the former, XP should be awarded based on results not methods. I should get XP for completing my goals. So no matter how I complete them, I get the same XP. Every approach is equally valid as every other approach.
For the latter, XP should be awarded for killing things (since that's what the game is primarily about).
Imho DOS is trying to be the former, not the latter, but that's clearly not a universal belief.