I guess we are going to have to agree to disagree, because I have no idea really what you are talking about. I can't address hearsay. My experience is no more or less valid than someone else's experience. But I can address the written mechanics of the game and the provided examples of play. I would presume Gygax counts as a designer of D&D, so I can address in particular the modules he wrote and whether they reward snatch and grab and whether his designs privilege something other than combat as the functional way to "win". And I think all the textual evidence is on my side.
Given the harsh rules on disengaging from melee, the idea of snatching someone's purse or loot without killing them first is somehow optimal is... bizarre in the extreme and I never once saw it work that way in practice, even ignoring the problems of snowballing encounters that definitely would come up in Gygaxian designs if you weren't focused on killing a single encounter as fast and as stealthy as possible.
I think you and others are confusing a single principle of Gygaxian skillful play, that is, "Don't get into unnecessary combats" with the whole or primary focus of Gygaxian play. I think this is obvious from your textual example of wandering monsters, which you can proof text from Gygax's writings. Gygaxian play was very much taken from his experience as a wargamer and very much focused on combat as a central pillar if not the central pillar of RPG play. We don't have to text proof from later designs in the Hickman era like Dragonlance or Ravenloft (which are arguably more about avoiding combat than anything Gygax wrote).