MK, the Occam Razor in its original definition is:
«frustra fit per plura quod potest fieri per pauciora»
Literally: “It’s useless (to make something) through multiple what can be done through a smaller number”
You explained it very well with the butler example. The Razor is not necessarily a simple explanation, rather it is an explanation that fits without increasing the system’s complexity for no reason. Every increase in the system’s complexity must be necessary.
So the butler could have done a number of complex actions (hence NOT a simple explanation), but if the theory about his actions fits the evidence and explains it all, without adding complex external elements (like Yetis), then the theory is correct.
There are a number of coincidences in the real world, so that two theories could fit precisely in the same way, but this is a quite rare exception.
From a phylosophical standpoint, the non-complex theory that fits is not only probable, it’s flat-out correct: because there can be only one non-complex explanation that fits (again, this is theoretically speaking).
I do find that the murder theory fits. Or, at least the presence of other people that forced the group to leave the tent. This would explain:
1) The most puzzling thing in this story, that is the group leaving without shoes. I personally have not heard another satisfactory explanation yet about this overlooked, huge piece of evidence.
2) The tent cut from the inside. It’s way more likely that a second party did cut it, than the Dyatlov group destroying their own mean of survival.
3) The injuries suffered by the Hill 3
These are three very important points. If we can’t explain those, we can’t explain anything.
As for the Ravine 4, I tend to believe that something snow-related happened. I read somewhere (I believe in this forum) an interesting theory about some meters of snow collapsing onto them. Yes, it’s not a very Occam-like explanation, but still they were in the wild and were found under meters of snow.
Surely, the injuries two of them suffered were of a different nature from the ones sustained by their comrades. Since there’s no agent that could have determined all the injuries by itself, I think it’s fair to assume that at least two agents were involved (i.e. hostile humans and snow). This remains consistent with the Razor, because the evidence calls for two different injury agents.